diff --git a/fastNLP/envs/set_backend.py b/fastNLP/envs/set_backend.py
index 6da62334..4d6fb915 100644
--- a/fastNLP/envs/set_backend.py
+++ b/fastNLP/envs/set_backend.py
@@ -5,7 +5,6 @@
 import os
 import json
 import sys
-import subprocess
 from collections import defaultdict