diff --git a/fastNLP/core/callbacks/topk_saver.py b/fastNLP/core/callbacks/topk_saver.py
index e2b0eb29..1ceea82e 100644
--- a/fastNLP/core/callbacks/topk_saver.py
+++ b/fastNLP/core/callbacks/topk_saver.py
@@ -31,7 +31,7 @@ class Saver:
             folder = Path.cwd()
         folder = Path(folder)
         if not folder.exists():
-            raise NotADirectoryError(f"Path '{folder.absolute()}' is not existed!")
+            folder.mkdir(parents=True, exist_ok=True)
         elif folder.is_file():
             raise ValueError("Parameter `folder` should be a directory instead of a file.")
 
diff --git a/fastNLP/core/controllers/loops/train_batch_loop.py b/fastNLP/core/controllers/loops/train_batch_loop.py
index 7dbe9775..cfb54111 100644
--- a/fastNLP/core/controllers/loops/train_batch_loop.py
+++ b/fastNLP/core/controllers/loops/train_batch_loop.py
@@ -36,7 +36,8 @@ class TrainBatchLoop(Loop):
                 raise e
 
             trainer.on_train_batch_begin(batch, indices)
-            self.batch_step_fn(trainer, batch)
+            with trainer.get_no_sync_context():  # 在多卡的时候可能需要关闭 sync
+                self.batch_step_fn(trainer, batch)
             trainer.global_forward_batches += 1
             trainer.batch_idx_in_epoch += 1
 
diff --git a/fastNLP/core/controllers/trainer.py b/fastNLP/core/controllers/trainer.py
index 779d3d83..3f346b56 100644
--- a/fastNLP/core/controllers/trainer.py
+++ b/fastNLP/core/controllers/trainer.py
@@ -696,8 +696,9 @@ class Trainer(TrainerEventTrigger):
         self.on_before_backward(outputs)
         loss = self.extract_loss_from_outputs(outputs)
         loss = loss / self.accumulation_steps
-        with self.get_no_sync_context():
-            self.driver.backward(loss)
+        # with self.get_no_sync_context():
+        #     self.driver.backward(loss)
+        self.driver.backward(loss)
         self.on_after_backward()
 
     def zero_grad(self):