diff --git a/backend/services/auth-service/src/application/services/user.service.ts b/backend/services/auth-service/src/application/services/user.service.ts
index 2929708b..48286d74 100644
--- a/backend/services/auth-service/src/application/services/user.service.ts
+++ b/backend/services/auth-service/src/application/services/user.service.ts
@@ -4,6 +4,8 @@ import {
   Phone,
   USER_REPOSITORY,
   UserRepository,
+  SYNCED_LEGACY_USER_REPOSITORY,
+  SyncedLegacyUserRepository,
 } from '@/domain';
 
 export interface UserProfileResult {
@@ -22,6 +24,8 @@ export class UserService {
   constructor(
     @Inject(USER_REPOSITORY)
     private readonly userRepository: UserRepository,
+    @Inject(SYNCED_LEGACY_USER_REPOSITORY)
+    private readonly syncedLegacyUserRepository: SyncedLegacyUserRepository,
   ) {}
 
   /**
@@ -50,20 +54,32 @@ export class UserService {
 
   /**
    * 根据手机号查找用户（用于P2P转账验证）
+   * 先查 V2 users 表，未找到再查 synced_legacy_users 表
    */
   async lookupByPhone(phone: string): Promise<{ exists: boolean; accountSequence?: string; nickname?: string }> {
     const phoneVO = Phone.create(phone);
-    const user = await this.userRepository.findByPhone(phoneVO);
 
-    if (!user || user.status !== 'ACTIVE') {
-      return { exists: false };
+    // 1. 先查 V2 用户表
+    const user = await this.userRepository.findByPhone(phoneVO);
+    if (user && user.status === 'ACTIVE') {
+      return {
+        exists: true,
+        accountSequence: user.accountSequence.value,
+        nickname: user.isKycVerified ? this.maskName(user.realName!) : user.phone.masked,
+      };
     }
 
-    return {
-      exists: true,
-      accountSequence: user.accountSequence.value,
-      nickname: user.isKycVerified ? this.maskName(user.realName!) : user.phone.masked,
-    };
+    // 2. 查 1.0 同步用户表（未迁移的老用户）
+    const legacyUser = await this.syncedLegacyUserRepository.findByPhone(phoneVO);
+    if (legacyUser && legacyUser.status === 'ACTIVE' && !legacyUser.migratedToV2) {
+      return {
+        exists: true,
+        accountSequence: legacyUser.accountSequence.value,
+        nickname: legacyUser.nickname || legacyUser.phone.masked,
+      };
+    }
+
+    return { exists: false };
   }
 
   /**