diff --git a/backend/services/referral-service/src/api/controllers/internal-referral-chain.controller.ts b/backend/services/referral-service/src/api/controllers/internal-referral-chain.controller.ts
index f139f19e..3338bfcc 100644
--- a/backend/services/referral-service/src/api/controllers/internal-referral-chain.controller.ts
+++ b/backend/services/referral-service/src/api/controllers/internal-referral-chain.controller.ts
@@ -58,8 +58,21 @@ export class InternalReferralChainController {
       };
     }
 
-    // ancestorPath 存储的是 userId (bigint)，需要转换为字符串
-    const ancestorPath = relationship.referralChain.map((id) => id.toString());
+    // referralChain 存储的是 userId (bigint)，需要转换为 accountSequence
+    // 因为 authorization-service 使用 accountSequence 来查询授权记录
+    const ancestorUserIds = relationship.referralChain;
+    const ancestorPath: string[] = [];
+
+    for (const ancestorUserId of ancestorUserIds) {
+      const ancestorRelationship = await this.referralRepo.findByUserId(ancestorUserId);
+      if (ancestorRelationship) {
+        ancestorPath.push(ancestorRelationship.accountSequence);
+      } else {
+        this.logger.warn(`[INTERNAL] Ancestor userId ${ancestorUserId} not found`);
+      }
+    }
+
+    this.logger.debug(`[INTERNAL] getReferralChain result: ${ancestorPath.length} ancestors`);
 
     return {
       accountSequence: relationship.accountSequence,
@@ -88,9 +101,18 @@ export class InternalReferralChainController {
     for (const seq of sequences) {
       const relationship = await this.referralRepo.findByAccountSequence(seq);
       if (relationship) {
+        // 转换 userId 为 accountSequence
+        const ancestorPath: string[] = [];
+        for (const ancestorUserId of relationship.referralChain) {
+          const ancestorRelationship = await this.referralRepo.findByUserId(ancestorUserId);
+          if (ancestorRelationship) {
+            ancestorPath.push(ancestorRelationship.accountSequence);
+          }
+        }
+
         results[seq] = {
           userId: relationship.userId.toString(),
-          ancestorPath: relationship.referralChain.map((id) => id.toString()),
+          ancestorPath,
           referrerId: relationship.referrerId?.toString() ?? null,
         };
       } else {