diff --git a/packages/shared/ai_service.py b/packages/shared/ai_service.py
index 637053eb7..f54860a2c 100755
--- a/packages/shared/ai_service.py
+++ b/packages/shared/ai_service.py
@@ -402,7 +402,7 @@ def _call_ai_cover_service(
                 logger.info("调用 MediaKit 抽帧: plan_id=%s video=%s", plan_id, primary_video_url[:80])
                 frames = client.extract_frames(
                     video_url=primary_video_url,
-                    strategy="SceneChange",  # 自动识别画面变化，选最佳帧
+                    strategy="TimeInterval",  # 按固定时间间隔，稳定性好，不易 OOM
                     max_frames=3,  # 减少到 3 帧，平衡速度和质量
                     poll_interval=2.0,  # 缩短轮询间隔
                     max_poll_attempts=60,  # 120秒超时