diff --git a/colossalai/inference/core/engine.py b/colossalai/inference/core/engine.py
index d86418bc9..742f53f76 100644
--- a/colossalai/inference/core/engine.py
+++ b/colossalai/inference/core/engine.py
@@ -1,4 +1,3 @@
-import copy
 import time
 from itertools import count
 from typing import Dict, List, Optional, Tuple, Union
@@ -110,7 +109,6 @@ class InferenceEngine:
 
         t_capture_begin = time.perf_counter()
 
-
         block_size = self.inference_config.block_size
         head_dim = self.model_config.hidden_size // self.model_config.num_attention_heads
 
@@ -133,7 +131,6 @@ class InferenceEngine:
         # NOTE: Capturing the largest batch size first may help reduce the
         # memory usage of CUDA graph.
         for batch_size in reversed(batch_size_capture_list):
-
             if self.verbose:
                 self.logger.info(f"batch size {batch_size} graph capturing")