diff --git a/packages/shared/ai_service.py b/packages/shared/ai_service.py
index c4a02a0fa..2550fb060 100755
--- a/packages/shared/ai_service.py
+++ b/packages/shared/ai_service.py
@@ -296,6 +296,62 @@ def _call_ai_recommend_service(
 # ── AI 封面生成 ──────────────────────────────────────────────────────────────
 
 
+
+def _transfer_cover_frame_to_storage(frame_url: str, plan_id: str) -> str:
+    """下载 MediaKit 帧图并上传到 OSS，返回公开可访问的 URL.
+
+    Args:
+        frame_url: MediaKit 返回的帧图 URL（内部/临时 URL）
+        plan_id: 剪辑计划 ID（用于生成存储路径）
+
+    Returns:
+        公开可访问的 URL；如果下载/上传失败则返回原始 URL
+    """
+    import tempfile
+    import uuid
+    from pathlib import Path
+
+    try:
+        import httpx
+
+        # 下载帧图
+        logger.info("下载 MediaKit 帧图: plan_id=%s url=%s", plan_id, frame_url[:80])
+        resp = httpx.get(frame_url, timeout=30, follow_redirects=True)
+        resp.raise_for_status()
+
+        if not resp.content:
+            logger.warning("MediaKit 帧图下载为空，返回原始 URL")
+            return frame_url
+
+        # 写入临时文件
+        with tempfile.NamedTemporaryFile(suffix=".jpg", delete=False) as tmp:
+            tmp.write(resp.content)
+            tmp_path = tmp.name
+
+        # 上传到 OSS
+        from packages.shared.storage import get_shared_storage_service
+        storage = get_shared_storage_service()
+        cover_key = f"covers/{plan_id}/mediakit_frame_{uuid.uuid4().hex[:8]}.jpg"
+        storage.upload_file(
+            file_or_path=tmp_path,
+            storage_key=cover_key,
+            content_type="image/jpeg",
+        )
+
+        # 获取公开 URL
+        public_url = storage.get_url(cover_key)
+        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
+        Path(tmp_path).unlink(missing_ok=True)
+
+        return public_url
+
+    except Exception as e:
+        logger.warning("封面帧图转存失败，返回原始 URL: %s", str(e))
+        return frame_url
+
+
 def _call_ai_cover_service(
     plan_id: str,
     asset_ids: List[str],
@@ -363,9 +419,12 @@ def _call_ai_cover_service(
                             timestamp,
                             image_url[:80],
                         )
+                        # MediaKit 返回的 URL 是临时内部 URL，浏览器无法直接访问
+                        # 需要下载到本地并重新上传到 OSS，返回公开可访问的 URL
+                        public_url = _transfer_cover_frame_to_storage(image_url, plan_id)
                         return {
                             "type": "ai_frame",
-                            "image_url": image_url,
+                            "image_url": public_url,
                             "frame_time": round(timestamp, 1),
                             "confidence": 0.85,
                         }