diff --git a/ppocr/data/rec/dataset_traversal.py b/ppocr/data/rec/dataset_traversal.py
index 5efba512c0e22dda1be17b121c0f12f42b74f2ee..ebee624ab74b2390323ab538627f459cb2353e8b 100755
--- a/ppocr/data/rec/dataset_traversal.py
+++ b/ppocr/data/rec/dataset_traversal.py
@@ -237,7 +237,7 @@ class SimpleReader(object):
 
         def get_device_num():
             if self.use_gpu:
-                gpus = os.environ.get("CUDA_VISIBLE_DEVICES", 1)
+                gpus = os.environ.get("CUDA_VISIBLE_DEVICES", '1')
                 gpu_num = len(gpus.split(','))
                 return gpu_num
             else: