diff --git a/packages/shared/ai_service.py b/packages/shared/ai_service.py
index b9ff8abcb..b74db337d 100755
--- a/packages/shared/ai_service.py
+++ b/packages/shared/ai_service.py
@@ -339,7 +339,7 @@ def _transfer_cover_frame_to_storage(frame_url: str, plan_id: str) -> str:
         )
 
         # 获取公开 URL
-        public_url = storage.get_url(cover_key)
+        public_url = storage.get_download_url(cover_key, expires_seconds=86400)
         logger.info("封面帧图已上传到 OSS: plan_id=%s key=%s url=%s", plan_id, cover_key, public_url[:80])
 
         # 清理临时文件