diff --git a/video-gen-api/app/api/v1/payments.py b/video-gen-api/app/api/v1/payments.py
index c83d2034..5c8f3840 100644
--- a/video-gen-api/app/api/v1/payments.py
+++ b/video-gen-api/app/api/v1/payments.py
@@ -153,6 +153,7 @@ async def wechat_callback(request: Request, db: AsyncSession = Depends(get_db)):
                 logger.warning("Wechatpay-Serial header missing, skipping signature verification")
         
         # 解密回调数据：使用 API v3 key
+        # 官方文档：https://pay.weixin.qq.com/doc/v3/merchant/4012071382
         import json
         body_data = json.loads(body_str) if body_str else {}
         resource = body_data.get("resource", {})
@@ -161,18 +162,32 @@ async def wechat_callback(request: Request, db: AsyncSession = Depends(get_db)):
             logger.error("WeChat callback resource not found")
             raise HTTPException(status_code=400, detail="数据格式错误")
         
+        # 验证加密算法（官方文档要求固定为 AEAD_AES_256_GCM）
+        algorithm = resource.get("algorithm", "")
+        if algorithm != "AEAD_AES_256_GCM":
+            logger.error(f"WeChat callback unsupported algorithm: {algorithm}")
+            raise HTTPException(status_code=400, detail="不支持的加密算法")
+        
         ciphertext = resource.get("ciphertext", "")
         associated_data = resource.get("associated_data", "")
         nonce_str = resource.get("nonce", "")
         
-        # 使用 AES-GCM 解密
+        # 参数验证
+        if not ciphertext:
+            logger.error("WeChat callback ciphertext is empty")
+            raise HTTPException(status_code=400, detail="密文为空")
+        if not nonce_str:
+            logger.error("WeChat callback nonce is empty")
+            raise HTTPException(status_code=400, detail="随机数为空")
+        
+        # 使用 AES-GCM 解密（符合官方文档规范）
         try:
             # API v3 key 需要转换为字节串
             api_v3_key_bytes = api_v3_key.encode('utf-8')
             
             # ciphertext 和 nonce 是 Base64 编码的，需要解码
-            ciphertext_bytes = b64decode(ciphertext) if ciphertext else b''
-            nonce_bytes = b64decode(nonce_str) if nonce_str else b''
+            ciphertext_bytes = b64decode(ciphertext)
+            nonce_bytes = b64decode(nonce_str)
             
             # associated_data 是字符串，直接编码
             associated_data_bytes = associated_data.encode('utf-8') if associated_data else b''
@@ -180,8 +195,8 @@ async def wechat_callback(request: Request, db: AsyncSession = Depends(get_db)):
             aesgcm = AESGCM(api_v3_key_bytes)
             decrypted_str = aesgcm.decrypt(ciphertext_bytes, associated_data_bytes, nonce_bytes)
         except InvalidTag:
-            logger.error("WeChat callback decryption failed: Invalid tag")
-            raise HTTPException(status_code=400, detail="数据解密失败")
+            logger.error("WeChat callback decryption failed: Invalid tag (key or data mismatch)")
+            raise HTTPException(status_code=400, detail="数据解密失败（密钥或数据不匹配）")
         except Exception as e:
             logger.error(f"WeChat callback decryption failed: {e}")
             raise HTTPException(status_code=400, detail="数据解密失败")