diff --git a/backend/services/blockchain-service/src/infrastructure/kafka/event-publisher.service.ts b/backend/services/blockchain-service/src/infrastructure/kafka/event-publisher.service.ts
index 94500a30..dd4b4723 100644
--- a/backend/services/blockchain-service/src/infrastructure/kafka/event-publisher.service.ts
+++ b/backend/services/blockchain-service/src/infrastructure/kafka/event-publisher.service.ts
@@ -103,6 +103,8 @@ export class EventPublisherService implements OnModuleInit, OnModuleDestroy {
       'blockchain.deposit.confirmed': 'blockchain.deposits',
       'blockchain.wallet.address.created': 'blockchain.wallets',
       'blockchain.transaction.broadcasted': 'blockchain.transactions',
+      // MPC 签名请求 - 发送到 mpc-service 消费的 topic
+      'blockchain.mpc.signing.requested': 'mpc.SigningRequested',
     };
     return topicMap[eventType] || 'blockchain.events';
   }
diff --git a/backend/services/blockchain-service/src/infrastructure/kafka/mpc-event-consumer.service.ts b/backend/services/blockchain-service/src/infrastructure/kafka/mpc-event-consumer.service.ts
index 36c99e88..fd948178 100644
--- a/backend/services/blockchain-service/src/infrastructure/kafka/mpc-event-consumer.service.ts
+++ b/backend/services/blockchain-service/src/infrastructure/kafka/mpc-event-consumer.service.ts
@@ -1,8 +1,10 @@
 /**
  * MPC Event Consumer Service for Blockchain Service
  *
- * Consumes MPC keygen completion events from mpc-service via Kafka.
- * Derives wallet addresses from public keys and publishes WalletAddressCreated events.
+ * Consumes MPC events from mpc-service via Kafka:
+ * - KeygenCompleted: derives wallet addresses from public keys
+ * - SigningCompleted: returns signature for hot wallet transfers
+ * - SessionFailed: handles keygen/signing failures
  */
 
 import { Injectable, Logger, OnModuleInit, OnModuleDestroy } from '@nestjs/common';
@@ -12,6 +14,7 @@ import { Kafka, Consumer, logLevel, EachMessagePayload } from 'kafkajs';
 // MPC Event Topics (events from mpc-service)
 export const MPC_TOPICS = {
   KEYGEN_COMPLETED: 'mpc.KeygenCompleted',
+  SIGNING_COMPLETED: 'mpc.SigningCompleted',
   SESSION_FAILED: 'mpc.SessionFailed',
 } as const;
 
@@ -34,15 +37,30 @@ export interface KeygenCompletedPayload {
   };
 }
 
+export interface SigningCompletedPayload {
+  sessionId: string;
+  partyId: string;
+  messageHash: string;
+  signature: string;
+  publicKey: string;
+  extraPayload?: {
+    userId: string;
+    username: string;
+    mpcSessionId: string;
+    source?: string;  // 'blockchain-service' | 'identity-service'
+  };
+}
+
 export interface SessionFailedPayload {
   sessionId: string;
   partyId: string;
-  sessionType: string;
+  sessionType: string;  // 'keygen' | 'sign'
   errorMessage: string;
   errorCode?: string;
   extraPayload?: {
     userId: string;
     username: string;
+    source?: string;
   };
 }
 
@@ -56,7 +74,9 @@ export class MpcEventConsumerService implements OnModuleInit, OnModuleDestroy {
   private isConnected = false;
 
   private keygenCompletedHandler?: MpcEventHandler<KeygenCompletedPayload>;
+  private signingCompletedHandler?: MpcEventHandler<SigningCompletedPayload>;
   private sessionFailedHandler?: MpcEventHandler<SessionFailedPayload>;
+  private signingFailedHandler?: MpcEventHandler<SessionFailedPayload>;
 
   constructor(private readonly configService: ConfigService) {}
 
@@ -120,13 +140,29 @@ export class MpcEventConsumerService implements OnModuleInit, OnModuleDestroy {
   }
 
   /**
-   * Register handler for session failed events
+   * Register handler for signing completed events
+   */
+  onSigningCompleted(handler: MpcEventHandler<SigningCompletedPayload>): void {
+    this.signingCompletedHandler = handler;
+    this.logger.log(`[REGISTER] SigningCompleted handler registered`);
+  }
+
+  /**
+   * Register handler for session failed events (keygen)
    */
   onSessionFailed(handler: MpcEventHandler<SessionFailedPayload>): void {
     this.sessionFailedHandler = handler;
     this.logger.log(`[REGISTER] SessionFailed handler registered`);
   }
 
+  /**
+   * Register handler for signing failed events
+   */
+  onSigningFailed(handler: MpcEventHandler<SessionFailedPayload>): void {
+    this.signingFailedHandler = handler;
+    this.logger.log(`[REGISTER] SigningFailed handler registered`);
+  }
+
   private async startConsuming(): Promise<void> {
     await this.consumer.run({
       eachMessage: async ({ topic, partition, message }: EachMessagePayload) => {
@@ -161,15 +197,35 @@ export class MpcEventConsumerService implements OnModuleInit, OnModuleDestroy {
               }
               break;
 
+            case MPC_TOPICS.SIGNING_COMPLETED:
+              this.logger.log(`[HANDLE] Processing SigningCompleted event`);
+              this.logger.log(`[HANDLE] sessionId: ${(payload as SigningCompletedPayload).sessionId}`);
+              this.logger.log(`[HANDLE] signature: ${(payload as SigningCompletedPayload).signature?.substring(0, 20)}...`);
+              if (this.signingCompletedHandler) {
+                await this.signingCompletedHandler(payload as SigningCompletedPayload);
+                this.logger.log(`[HANDLE] SigningCompleted handler completed successfully`);
+              } else {
+                this.logger.warn(`[HANDLE] No handler registered for SigningCompleted`);
+              }
+              break;
+
             case MPC_TOPICS.SESSION_FAILED:
               this.logger.log(`[HANDLE] Processing SessionFailed event`);
               this.logger.log(`[HANDLE] sessionType: ${(payload as SessionFailedPayload).sessionType}`);
               this.logger.log(`[HANDLE] errorMessage: ${(payload as SessionFailedPayload).errorMessage}`);
-              if (this.sessionFailedHandler) {
-                await this.sessionFailedHandler(payload as SessionFailedPayload);
-                this.logger.log(`[HANDLE] SessionFailed handler completed`);
+
+              const failedPayload = payload as SessionFailedPayload;
+              // Route to appropriate handler based on session type
+              if (failedPayload.sessionType === 'sign') {
+                if (this.signingFailedHandler) {
+                  await this.signingFailedHandler(failedPayload);
+                  this.logger.log(`[HANDLE] SigningFailed handler completed`);
+                }
               } else {
-                this.logger.warn(`[HANDLE] No handler registered for SessionFailed`);
+                if (this.sessionFailedHandler) {
+                  await this.sessionFailedHandler(failedPayload);
+                  this.logger.log(`[HANDLE] SessionFailed handler completed`);
+                }
               }
               break;
 
diff --git a/backend/services/blockchain-service/src/infrastructure/mpc/mpc-signing.client.ts b/backend/services/blockchain-service/src/infrastructure/mpc/mpc-signing.client.ts
index c2dfdc62..7f4fcea2 100644
--- a/backend/services/blockchain-service/src/infrastructure/mpc/mpc-signing.client.ts
+++ b/backend/services/blockchain-service/src/infrastructure/mpc/mpc-signing.client.ts
@@ -1,14 +1,23 @@
 /**
  * MPC Signing Client
  *
- * 调用 mpc-service 进行 MPC 签名
+ * 通过 Kafka 事件与 mpc-service 通信进行 MPC 签名
  * 用于热钱包的 ERC20 转账签名
+ *
+ * 事件流:
+ * blockchain-service → Kafka(mpc.SigningRequested) → mpc-service
+ * mpc-service → Kafka(mpc.SigningCompleted) → blockchain-service
  */
 
-import { Injectable, Logger } from '@nestjs/common';
+import { Injectable, Logger, OnModuleInit } from '@nestjs/common';
 import { ConfigService } from '@nestjs/config';
-import { HttpService } from '@nestjs/axios';
-import { firstValueFrom } from 'rxjs';
+import { randomUUID } from 'crypto';
+import { EventPublisherService } from '@/infrastructure/kafka/event-publisher.service';
+import {
+  MpcEventConsumerService,
+  SigningCompletedPayload,
+  SessionFailedPayload,
+} from '@/infrastructure/kafka/mpc-event-consumer.service';
 
 export interface CreateSigningInput {
   username: string;
@@ -21,20 +30,31 @@ export interface SigningResult {
   signature?: string;
 }
 
+// 签名结果回调
+type SigningCallback = (signature: string | null, error?: string) => void;
+
+// MPC 签名请求 Topic
+export const MPC_SIGNING_TOPIC = 'mpc.SigningRequested';
+
 @Injectable()
-export class MpcSigningClient {
+export class MpcSigningClient implements OnModuleInit {
   private readonly logger = new Logger(MpcSigningClient.name);
-  private readonly mpcServiceUrl: string;
   private readonly hotWalletUsername: string;
   private readonly hotWalletAddress: string;
-  private readonly pollingIntervalMs: number = 2000;
-  private readonly maxPollingAttempts: number = 150; // 5 minutes max
+  private readonly signingTimeoutMs: number = 300000; // 5 minutes
+
+  // 待处理的签名请求回调 Map<sessionId, { resolve, reject, timeout }>
+  private pendingRequests: Map<string, {
+    resolve: (signature: string) => void;
+    reject: (error: Error) => void;
+    timeout: NodeJS.Timeout;
+  }> = new Map();
 
   constructor(
     private readonly configService: ConfigService,
-    private readonly httpService: HttpService,
+    private readonly eventPublisher: EventPublisherService,
+    private readonly mpcEventConsumer: MpcEventConsumerService,
   ) {
-    this.mpcServiceUrl = this.configService.get<string>('MPC_SERVICE_URL', 'http://localhost:3013');
     this.hotWalletUsername = this.configService.get<string>('HOT_WALLET_USERNAME', '');
     this.hotWalletAddress = this.configService.get<string>('HOT_WALLET_ADDRESS', '');
 
@@ -45,9 +65,16 @@ export class MpcSigningClient {
       this.logger.warn('[INIT] HOT_WALLET_ADDRESS not configured');
     }
 
-    this.logger.log(`[INIT] MPC Service URL: ${this.mpcServiceUrl}`);
     this.logger.log(`[INIT] Hot Wallet Username: ${this.hotWalletUsername || '(not configured)'}`);
     this.logger.log(`[INIT] Hot Wallet Address: ${this.hotWalletAddress || '(not configured)'}`);
+    this.logger.log(`[INIT] Using Kafka event-driven signing`);
+  }
+
+  async onModuleInit() {
+    // 注册签名完成和失败事件处理器
+    this.mpcEventConsumer.onSigningCompleted(this.handleSigningCompleted.bind(this));
+    this.mpcEventConsumer.onSigningFailed(this.handleSigningFailed.bind(this));
+    this.logger.log('[INIT] MPC signing event handlers registered');
   }
 
   /**
@@ -72,66 +99,7 @@ export class MpcSigningClient {
   }
 
   /**
-   * 创建 MPC 签名会话
-   */
-  async createSigningSession(messageHash: string): Promise<{ sessionId: string; status: string }> {
-    this.logger.log(`[SIGN] Creating signing session for messageHash: ${messageHash.slice(0, 16)}...`);
-
-    if (!this.hotWalletUsername) {
-      throw new Error('Hot wallet username not configured');
-    }
-
-    const response = await firstValueFrom(
-      this.httpService.post<{
-        sessionId: string;
-        status: string;
-      }>(
-        `${this.mpcServiceUrl}/api/v1/mpc/sign`,
-        {
-          username: this.hotWalletUsername,
-          messageHash,
-        },
-        {
-          headers: { 'Content-Type': 'application/json' },
-          timeout: 30000,
-        },
-      ),
-    );
-
-    this.logger.log(`[SIGN] Session created: ${response.data.sessionId}`);
-    return {
-      sessionId: response.data.sessionId,
-      status: response.data.status,
-    };
-  }
-
-  /**
-   * 获取签名会话状态
-   */
-  async getSigningStatus(sessionId: string): Promise<SigningResult> {
-    const response = await firstValueFrom(
-      this.httpService.get<{
-        sessionId: string;
-        status: string;
-        signature?: string;
-      }>(
-        `${this.mpcServiceUrl}/api/v1/mpc/sign/${sessionId}/status`,
-        {
-          headers: { 'Content-Type': 'application/json' },
-          timeout: 10000,
-        },
-      ),
-    );
-
-    return {
-      sessionId: response.data.sessionId,
-      status: response.data.status,
-      signature: response.data.signature,
-    };
-  }
-
-  /**
-   * 签名消息（创建会话并等待完成）
+   * 签名消息（通过 Kafka 事件驱动）
    *
    * @param messageHash 要签名的消息哈希 (hex string with 0x prefix)
    * @returns 签名结果 (hex string)
@@ -139,49 +107,91 @@ export class MpcSigningClient {
   async signMessage(messageHash: string): Promise<string> {
     this.logger.log(`[SIGN] Starting MPC signing for: ${messageHash.slice(0, 16)}...`);
 
-    // Step 1: 创建签名会话
-    const session = await this.createSigningSession(messageHash);
-    this.logger.log(`[SIGN] Session ID: ${session.sessionId}`);
-
-    // Step 2: 轮询等待签名完成
-    const result = await this.pollForCompletion(session.sessionId);
-
-    if (result.status === 'completed' && result.signature) {
-      this.logger.log(`[SIGN] Signature obtained: ${result.signature.slice(0, 20)}...`);
-      return result.signature;
+    if (!this.hotWalletUsername) {
+      throw new Error('Hot wallet username not configured');
     }
 
-    throw new Error(`MPC signing failed with status: ${result.status}`);
+    const sessionId = randomUUID();
+    this.logger.log(`[SIGN] Session ID: ${sessionId}`);
+
+    // 创建 Promise 等待签名结果
+    const signaturePromise = new Promise<string>((resolve, reject) => {
+      // 设置超时
+      const timeout = setTimeout(() => {
+        this.pendingRequests.delete(sessionId);
+        reject(new Error(`MPC signing timeout after ${this.signingTimeoutMs}ms`));
+      }, this.signingTimeoutMs);
+
+      // 保存到待处理队列
+      this.pendingRequests.set(sessionId, { resolve, reject, timeout });
+    });
+
+    // 发布签名请求事件到 Kafka
+    try {
+      await this.eventPublisher.publish({
+        eventType: 'blockchain.mpc.signing.requested',
+        toPayload: () => ({
+          sessionId,
+          userId: 'system', // 系统热钱包
+          username: this.hotWalletUsername,
+          messageHash,
+          source: 'blockchain-service',
+        }),
+        eventId: sessionId,
+        occurredAt: new Date(),
+      });
+
+      this.logger.log(`[SIGN] Signing request published to Kafka: sessionId=${sessionId}`);
+    } catch (error) {
+      // 发布失败，清理待处理队列
+      const pending = this.pendingRequests.get(sessionId);
+      if (pending) {
+        clearTimeout(pending.timeout);
+        this.pendingRequests.delete(sessionId);
+      }
+      throw error;
+    }
+
+    // 等待签名结果
+    const signature = await signaturePromise;
+    this.logger.log(`[SIGN] Signature obtained: ${signature.slice(0, 20)}...`);
+    return signature;
   }
 
   /**
-   * 轮询等待签名完成
+   * 处理签名完成事件
    */
-  private async pollForCompletion(sessionId: string): Promise<SigningResult> {
-    for (let attempt = 0; attempt < this.maxPollingAttempts; attempt++) {
-      const result = await this.getSigningStatus(sessionId);
+  private async handleSigningCompleted(payload: SigningCompletedPayload): Promise<void> {
+    const sessionId = payload.sessionId;
+    this.logger.log(`[EVENT] Signing completed: sessionId=${sessionId}`);
 
-      this.logger.debug(`[POLL] Session ${sessionId}: status=${result.status}, attempt=${attempt + 1}`);
+    const pending = this.pendingRequests.get(sessionId);
+    if (pending) {
+      clearTimeout(pending.timeout);
+      this.pendingRequests.delete(sessionId);
 
-      if (result.status === 'completed') {
-        return result;
+      if (payload.signature) {
+        pending.resolve(payload.signature);
+      } else {
+        pending.reject(new Error('Signing completed but no signature returned'));
       }
-
-      if (result.status === 'failed' || result.status === 'expired') {
-        return result;
-      }
-
-      // 等待下一次轮询
-      await this.sleep(this.pollingIntervalMs);
+    } else {
+      this.logger.warn(`[EVENT] No pending request for sessionId=${sessionId}`);
     }
-
-    return {
-      sessionId,
-      status: 'timeout',
-    };
   }
 
-  private sleep(ms: number): Promise<void> {
-    return new Promise(resolve => setTimeout(resolve, ms));
+  /**
+   * 处理签名失败事件
+   */
+  private async handleSigningFailed(payload: SessionFailedPayload): Promise<void> {
+    const sessionId = payload.sessionId;
+    this.logger.warn(`[EVENT] Signing failed: sessionId=${sessionId}, error=${payload.errorMessage}`);
+
+    const pending = this.pendingRequests.get(sessionId);
+    if (pending) {
+      clearTimeout(pending.timeout);
+      this.pendingRequests.delete(sessionId);
+      pending.reject(new Error(`MPC signing failed: ${payload.errorMessage}`));
+    }
   }
 }
diff --git a/backend/services/mpc-service/src/application/event-handlers/signing-requested.handler.ts b/backend/services/mpc-service/src/application/event-handlers/signing-requested.handler.ts
index 604e0e39..5ab0b337 100644
--- a/backend/services/mpc-service/src/application/event-handlers/signing-requested.handler.ts
+++ b/backend/services/mpc-service/src/application/event-handlers/signing-requested.handler.ts
@@ -1,8 +1,12 @@
 /**
  * SigningRequested Event Handler
  *
- * Handles signing requests from identity-service via Kafka.
+ * Handles signing requests from identity-service and blockchain-service via Kafka.
  * Processes the signing and publishes completion/failure events.
+ *
+ * 事件流:
+ * - identity-service → mpc.SigningRequested → mpc-service → mpc.SigningCompleted → identity-service
+ * - blockchain-service → mpc.SigningRequested → mpc-service → mpc.SigningCompleted → blockchain-service
  */
 
 import { Injectable, Logger, OnModuleInit } from '@nestjs/common';
@@ -38,8 +42,10 @@ export class SigningRequestedHandler implements OnModuleInit {
   private async handleMessage(topic: string, payload: Record<string, unknown>): Promise<void> {
     const data = payload as unknown as SigningRequestedPayload;
     const { sessionId, userId, username, messageHash, userShare } = data;
+    // source 标识请求来源: 'blockchain-service' | 'identity-service'
+    const source = (data as any).source || 'identity-service';
 
-    this.logger.log(`Processing signing request: userId=${userId}, username=${username}, sessionId=${sessionId}`);
+    this.logger.log(`Processing signing request: userId=${userId}, username=${username}, sessionId=${sessionId}, source=${source}`);
 
     try {
       // Step 1: Create signing session via mpc-system
@@ -65,11 +71,12 @@ export class SigningRequestedHandler implements OnModuleInit {
           '', // publicKey - not needed for signing result
         );
 
-        // Add extra payload for identity-service
+        // Add extra payload for the requesting service (identity-service or blockchain-service)
         (completedEvent as any).extraPayload = {
           userId,
           username,
           mpcSessionId,
+          source,
         };
 
         await this.eventPublisher.publishWithRetry(completedEvent);
@@ -82,10 +89,10 @@ export class SigningRequestedHandler implements OnModuleInit {
           SessionType.SIGN,
           `Signing failed with status: ${result.status}`,
         );
-        (failedEvent as any).extraPayload = { userId, username };
+        (failedEvent as any).extraPayload = { userId, username, source };
 
         await this.eventPublisher.publishWithRetry(failedEvent);
-        this.logger.warn(`Signing failed: userId=${userId}, status=${result.status}`);
+        this.logger.warn(`Signing failed: userId=${userId}, status=${result.status}, source=${source}`);
       }
     } catch (error) {
       this.logger.error(`Signing processing error: userId=${userId}`, error);
@@ -97,7 +104,7 @@ export class SigningRequestedHandler implements OnModuleInit {
         SessionType.SIGN,
         error instanceof Error ? error.message : 'Unknown error',
       );
-      (failedEvent as any).extraPayload = { userId, username };
+      (failedEvent as any).extraPayload = { userId, username, source };
 
       try {
         await this.eventPublisher.publishWithRetry(failedEvent);
diff --git a/backend/services/mpc-service/src/infrastructure/messaging/kafka/event-consumer.service.ts b/backend/services/mpc-service/src/infrastructure/messaging/kafka/event-consumer.service.ts
index e0ec71a4..6e0509b6 100644
--- a/backend/services/mpc-service/src/infrastructure/messaging/kafka/event-consumer.service.ts
+++ b/backend/services/mpc-service/src/infrastructure/messaging/kafka/event-consumer.service.ts
@@ -2,7 +2,7 @@
  * Event Consumer Service
  *
  * Consumes domain events from Kafka for async processing.
- * Handles keygen and signing requests from identity-service.
+ * Handles keygen and signing requests from identity-service and blockchain-service.
  */
 
 import { Injectable, Logger, OnModuleInit, OnModuleDestroy } from '@nestjs/common';
@@ -31,6 +31,7 @@ export interface SigningRequestedPayload {
   username: string;
   messageHash: string;
   userShare?: string;
+  source?: string;  // 'identity-service' | 'blockchain-service'
 }
 
 export type MessageHandler = (topic: string, payload: Record<string, unknown>) => Promise<void>;