diff --git a/ding/worker/collector/base_serial_evaluator.py b/ding/worker/collector/base_serial_evaluator.py
index fab50dd27c..f5a31319ec 100644
--- a/ding/worker/collector/base_serial_evaluator.py
+++ b/ding/worker/collector/base_serial_evaluator.py
@@ -55,11 +55,11 @@ def should_eval(self, train_iter: int) -> bool:
 
     @abstractmethod
     def eval(
-        self,
-        save_ckpt_fn: Callable = None,
-        train_iter: int = -1,
-        envstep: int = -1,
-        n_episode: Optional[int] = None
+            self,
+            save_ckpt_fn: Callable = None,
+            train_iter: int = -1,
+            envstep: int = -1,
+            n_episode: Optional[int] = None
     ) -> Any:
         raise NotImplementedError