diff --git a/backend/mpc-system/services/service-party-app/electron/main.ts b/backend/mpc-system/services/service-party-app/electron/main.ts
index 3c323cdf..d2892a49 100644
--- a/backend/mpc-system/services/service-party-app/electron/main.ts
+++ b/backend/mpc-system/services/service-party-app/electron/main.ts
@@ -679,11 +679,19 @@ function setupIpcHandlers() {
           threshold: activeKeygenSession.threshold,
         });
 
-        // 100% 可靠方案：延迟检查会话状态，如果所有人都已加入则触发 keygen
-        // 这样即使错过 session_started 事件也能正常工作
-        setTimeout(() => {
+        // 关键步骤：立即预订阅消息流
+        // 这确保在其他方开始发送 TSS 消息时，我们已经准备好接收和缓冲
+        // 即使 keygen 进程还没启动，消息也不会丢失
+        if (tssHandler && 'prepareForKeygen' in tssHandler) {
+          debugLog.info('tss', `Preparing for keygen: subscribing to messages for session ${sessionId}`);
+          (tssHandler as { prepareForKeygen: (sessionId: string, partyId: string) => void }).prepareForKeygen(sessionId, partyId);
+        }
+
+        // 立即检查会话状态并触发 keygen（不再延迟）
+        // 使用 setImmediate 确保在当前事件循环结束后立即执行
+        setImmediate(() => {
           checkAndTriggerKeygen(sessionId);
-        }, 1000); // 延迟 1 秒等待可能的事件到达
+        });
       }
       return { success: true, data: result };
     } catch (error) {
@@ -752,10 +760,16 @@ function setupIpcHandlers() {
             threshold: activeKeygenSession.threshold,
           });
 
-          // 100% 可靠方案：延迟检查会话状态，如果所有人都已加入则触发 keygen
-          setTimeout(() => {
+          // 关键步骤：立即预订阅消息流
+          if (tssHandler && 'prepareForKeygen' in tssHandler) {
+            debugLog.info('tss', `Initiator preparing for keygen: subscribing to messages for session ${result.session_id}`);
+            (tssHandler as { prepareForKeygen: (sessionId: string, partyId: string) => void }).prepareForKeygen(result.session_id, partyId);
+          }
+
+          // 立即检查会话状态并触发 keygen（不再延迟）
+          setImmediate(() => {
             checkAndTriggerKeygen(result.session_id);
-          }, 1000);
+          });
         } else {
           console.warn('Initiator failed to join session');
         }
diff --git a/backend/mpc-system/services/service-party-app/electron/modules/tss-handler.ts b/backend/mpc-system/services/service-party-app/electron/modules/tss-handler.ts
index 32f02a8c..433e1364 100644
--- a/backend/mpc-system/services/service-party-app/electron/modules/tss-handler.ts
+++ b/backend/mpc-system/services/service-party-app/electron/modules/tss-handler.ts
@@ -71,6 +71,8 @@ export class TSSHandler extends EventEmitter {
     payload: Buffer;
   }> = [];
   private isProcessReady = false;
+  // 是否已预订阅消息（用于在 keygen 启动前就开始缓冲消息）
+  private isPrepared = false;
 
   constructor(grpcClient: GrpcClient, database?: DatabaseManager) {
     super();
@@ -113,6 +115,51 @@ export class TSSHandler extends EventEmitter {
     return binaryName;
   }
 
+  /**
+   * 预订阅消息流 - 在 joinSession 后立即调用
+   * 这确保在其他方开始发送消息时，我们已经准备好接收和缓冲
+   *
+   * @param sessionId 会话 ID
+   * @param partyId 自己的 party ID
+   */
+  prepareForKeygen(sessionId: string, partyId: string): void {
+    if (this.isPrepared) {
+      console.log('[TSS] Already prepared for keygen, skip');
+      return;
+    }
+
+    console.log(`[TSS] Preparing for keygen: session=${sessionId.substring(0, 8)}..., party=${partyId.substring(0, 8)}...`);
+
+    this.sessionId = sessionId;
+    this.partyId = partyId;
+    this.isPrepared = true;
+    this.messageBuffer = [];
+
+    // 立即订阅消息流，开始缓冲消息
+    // 使用 bound 方法确保 this 上下文正确
+    this.grpcClient.on('mpcMessage', this.handleIncomingMessage.bind(this));
+    this.grpcClient.subscribeMessages(sessionId, partyId);
+
+    console.log('[TSS] Message subscription started, buffering enabled');
+  }
+
+  /**
+   * 取消预订阅
+   */
+  cancelPrepare(): void {
+    if (!this.isPrepared) {
+      return;
+    }
+
+    console.log('[TSS] Canceling prepare');
+    this.isPrepared = false;
+    this.messageBuffer = [];
+    this.grpcClient.removeAllListeners('mpcMessage');
+    this.grpcClient.unsubscribeMessages();
+    this.sessionId = null;
+    this.partyId = null;
+  }
+
   /**
    * 参与 Keygen 协议
    */
@@ -128,13 +175,19 @@ export class TSSHandler extends EventEmitter {
       throw new Error('TSS protocol already running');
     }
 
+    // 检查是否已经预订阅
+    const wasPrepared = this.isPrepared && this.sessionId === sessionId;
+    const bufferedCount = this.messageBuffer.length;
+
+    console.log(`[TSS] Starting keygen: wasPrepared=${wasPrepared}, bufferedMessages=${bufferedCount}`);
+
     this.sessionId = sessionId;
     this.partyId = partyId;
     this.partyIndex = partyIndex;
     this.participants = participants;
     this.isRunning = true;
     this.isProcessReady = false;
-    this.messageBuffer = []; // 清空消息缓冲
+    // 注意：不清空消息缓冲，保留预订阅阶段收到的消息
 
     // 构建 party index map
     this.partyIndexMap.clear();
@@ -163,9 +216,15 @@ export class TSSHandler extends EventEmitter {
 
         let resultData = '';
 
-        // 先订阅消息（可能在进程就绪前就收到消息，会被缓冲）
-        this.grpcClient.on('mpcMessage', this.handleIncomingMessage.bind(this));
-        this.grpcClient.subscribeMessages(sessionId, partyId);
+        // 如果没有预订阅，现在订阅消息
+        // 如果已经预订阅，消息监听器已经注册，不需要重复注册
+        if (!wasPrepared) {
+          console.log('[TSS] Subscribing to messages (not prepared before)');
+          this.grpcClient.on('mpcMessage', this.handleIncomingMessage.bind(this));
+          this.grpcClient.subscribeMessages(sessionId, partyId);
+        } else {
+          console.log(`[TSS] Using existing subscription, ${bufferedCount} messages buffered`);
+        }
 
         // 处理标准输出 (JSON 消息)
         this.tssProcess.stdout?.on('data', (data: Buffer) => {
@@ -203,6 +262,7 @@ export class TSSHandler extends EventEmitter {
           const completedSessionId = this.sessionId;
           this.isRunning = false;
           this.isProcessReady = false;
+          this.isPrepared = false;
           this.messageBuffer = [];
           this.tssProcess = null;
           // 清理消息监听器，防止下次 keygen 时重复注册
@@ -237,6 +297,7 @@ export class TSSHandler extends EventEmitter {
         this.tssProcess.on('error', (err) => {
           this.isRunning = false;
           this.isProcessReady = false;
+          this.isPrepared = false;
           this.messageBuffer = [];
           this.tssProcess = null;
           // 清理消息监听器
@@ -246,6 +307,7 @@ export class TSSHandler extends EventEmitter {
 
       } catch (err) {
         this.isRunning = false;
+        this.isPrepared = false;
         reject(err);
       }
     });
@@ -296,6 +358,11 @@ export class TSSHandler extends EventEmitter {
 
   /**
    * 处理从 gRPC 接收的 MPC 消息（带去重）
+   *
+   * 消息处理状态：
+   * 1. isPrepared=true, isRunning=false: 预订阅阶段，缓冲消息
+   * 2. isPrepared=true, isRunning=true, isProcessReady=false: 进程启动中，缓冲消息
+   * 3. isPrepared=true, isRunning=true, isProcessReady=true: 进程就绪，直接发送
    */
   private handleIncomingMessage(message: {
     messageId: string;
@@ -311,16 +378,22 @@ export class TSSHandler extends EventEmitter {
       }
     }
 
-    // 如果进程未就绪，缓冲消息
-    if (!this.isProcessReady || !this.tssProcess || !this.tssProcess.stdin) {
-      if (this.isRunning) {
-        console.log(`[TSS] Buffering message from ${message.fromParty.substring(0, 8)}... (process not ready)`);
-        this.messageBuffer.push(message);
-      }
+    // 如果进程就绪，直接发送
+    if (this.isProcessReady && this.tssProcess?.stdin) {
+      this.sendMessageToProcess(message);
       return;
     }
 
-    this.sendMessageToProcess(message);
+    // 如果已预订阅或正在运行，缓冲消息
+    // 这确保在任何阶段收到的消息都不会丢失
+    if (this.isPrepared || this.isRunning) {
+      console.log(`[TSS] Buffering message from ${message.fromParty.substring(0, 8)}... (prepared=${this.isPrepared}, running=${this.isRunning}, ready=${this.isProcessReady})`);
+      this.messageBuffer.push(message);
+      return;
+    }
+
+    // 既没预订阅也没运行，忽略消息
+    console.log(`[TSS] Ignoring message from ${message.fromParty.substring(0, 8)}... (not prepared)`);
   }
 
   /**
@@ -383,6 +456,7 @@ export class TSSHandler extends EventEmitter {
     }
     this.isRunning = false;
     this.isProcessReady = false;
+    this.isPrepared = false;
     this.messageBuffer = [];
     this.grpcClient.removeAllListeners('mpcMessage');
   }
@@ -393,6 +467,13 @@ export class TSSHandler extends EventEmitter {
   getIsRunning(): boolean {
     return this.isRunning;
   }
+
+  /**
+   * 检查是否已预订阅
+   */
+  getIsPrepared(): boolean {
+    return this.isPrepared;
+  }
 }
 
 /**