diff --git a/backend/api_service/app/routers/accounts.py b/backend/api_service/app/routers/accounts.py
index df0b9be..4aec281 100644
--- a/backend/api_service/app/routers/accounts.py
+++ b/backend/api_service/app/routers/accounts.py
@@ -218,7 +218,12 @@ async def _verify_weibo_cookie(cookie_str: str) -> dict:
             headers=WEIBO_HEADERS,
             cookies=cookies,
         )
-        data = resp.json()
+        try:
+            data = resp.json()
+        except Exception:
+            # 非 JSON 响应（可能是 GBK 编码的登录页），视为 Cookie 失效
+            return {"valid": False, "uid": None, "screen_name": None}
+
         if data.get("ok") != 1:
             return {"valid": False, "uid": None, "screen_name": None}
 
@@ -237,7 +242,7 @@ async def _verify_weibo_cookie(cookie_str: str) -> dict:
                 uid = str(user.get("idstr", user.get("id", "")))
                 screen_name = user.get("screen_name", "")
         except Exception:
-            pass  # profile info is optional, login check already passed
+            pass
 
         return {"valid": True, "uid": uid, "screen_name": screen_name}
 
@@ -336,7 +341,10 @@ async def _get_super_topics(cookie_str: str, weibo_uid: str = "") -> List[dict]:
                 headers=headers,
                 cookies=cookies,
             )
-            data = resp.json()
+            try:
+                data = resp.json()
+            except Exception:
+                break
             if data.get("ok") != 1:
                 break
 
@@ -413,7 +421,10 @@ async def _do_signin(cookie_str: str, topic_title: str, containerid: str) -> dic
                 headers=headers,
                 cookies=cookies,
             )
-            data = resp.json()
+            try:
+                data = resp.json()
+            except Exception:
+                return {"status": "failed", "message": f"非JSON响应: {resp.text[:100]}"}
             code = str(data.get("code", ""))
             msg = data.get("msg", "")