diff --git a/qcloud_cos/cos_client.py b/qcloud_cos/cos_client.py
index 4e10179..8174bfc 100644
--- a/qcloud_cos/cos_client.py
+++ b/qcloud_cos/cos_client.py
@@ -4696,7 +4696,7 @@ def ci_auditing_text_submit(self, Bucket, Key, DetectType, Content=None, Callbac
         if Key:
             Input['Object'] = Key
         if Content:
-            Input['Content'] = base64.b64encode(Content)
+            Input['Content'] = base64.b64encode(Content).decode('UTF-8')
 
         conf = {
         }