diff --git a/backend/services/referral-service/src/application/event-handlers/user-registered.handler.ts b/backend/services/referral-service/src/application/event-handlers/user-registered.handler.ts
index 8a63ef03..2fc86286 100644
--- a/backend/services/referral-service/src/application/event-handlers/user-registered.handler.ts
+++ b/backend/services/referral-service/src/application/event-handlers/user-registered.handler.ts
@@ -61,11 +61,13 @@ export class UserRegisteredHandler implements OnModuleInit {
 
     try {
       this.logger.log(
-        `Processing ${event.eventType} event: userId=${payload.userId}, accountSequence=${payload.accountSequence}, inviterSequence=${payload.inviterSequence}`,
+        `Processing ${event.eventType} event: accountSequence=${payload.accountSequence}, inviterSequence=${payload.inviterSequence}`,
       );
 
+      // 使用 accountSequence 作为 userId，因为 identity-service 的 userId 是内部自增ID，
+      // 在事件发布时可能还是临时值 0，而 accountSequence 是全局唯一的业务标识
       const command = new CreateReferralRelationshipCommand(
-        BigInt(payload.userId),
+        BigInt(payload.accountSequence), // 使用 accountSequence 作为 userId
         payload.accountSequence,
         null, // referrerCode - 不通过推荐码查找
         payload.inviterSequence, // 通过 accountSequence 查找推荐人
@@ -73,11 +75,11 @@ export class UserRegisteredHandler implements OnModuleInit {
 
       const result = await this.referralService.createReferralRelationship(command);
       this.logger.log(
-        `Created referral relationship for user ${payload.userId} (seq: ${payload.accountSequence}), code: ${result.referralCode}, inviter: ${payload.inviterSequence ?? 'none'}`,
+        `Created referral relationship for accountSequence=${payload.accountSequence}, code: ${result.referralCode}, inviter: ${payload.inviterSequence ?? 'none'}`,
       );
     } catch (error) {
       this.logger.error(
-        `Failed to create referral relationship for user ${payload.userId} (seq: ${payload.accountSequence}):`,
+        `Failed to create referral relationship for accountSequence=${payload.accountSequence}:`,
         error,
       );
     }