diff --git a/fastNLP/core/drivers/torch_driver/torch_driver.py b/fastNLP/core/drivers/torch_driver/torch_driver.py
index 3630b593..2a04e62f 100644
--- a/fastNLP/core/drivers/torch_driver/torch_driver.py
+++ b/fastNLP/core/drivers/torch_driver/torch_driver.py
@@ -255,13 +255,14 @@ class TorchDriver(Driver):
                 logger.debug("Load model...")
 
         # 3. 加载fp16的状态
-        if 'grad_scaler_state_dict' in states:
-            grad_scaler_state_dict = states.pop('grad_scaler_state_dict')
-            if not isinstance(self.grad_scaler, DummyGradScaler):
-                self.grad_scaler.load_state_dict(grad_scaler_state_dict)
-                self.auto_cast = torch.cuda.amp.autocast
+        if "grad_scaler_state_dict" in states:
+            grad_scaler_state_dict = states.pop("grad_scaler_state_dict")
+            if isinstance(self.grad_scaler, DummyGradScaler):
+                self.auto_cast, _grad_scaler = _build_fp16_env(dummy=False)
+                self.grad_scaler = _grad_scaler()
                 self.fp16 = True
-                logger.debug("Load grad_scaler state dict...")
+            self.grad_scaler.load_state_dict(grad_scaler_state_dict)
+            logger.debug("Load grad_scaler state dict...")
         elif not isinstance(self.grad_scaler, DummyGradScaler):
             logger.warning(f"Checkpoint {folder} is not trained with fp16=True, while resume to a fp16=True training, "
                            f"the training process may be unstable.")