diff --git a/qcloud_cos/cos_client.py b/qcloud_cos/cos_client.py
index d3dc79af..c15ec991 100644
--- a/qcloud_cos/cos_client.py
+++ b/qcloud_cos/cos_client.py
@@ -151,7 +151,7 @@ def __init__(self, conf, retry=1, session=None):
         else:
             self._session = session
 
-    def get_auth(self, Method, Bucket, Key=None, Expired=10000, headers={}, params={}):
+    def get_auth(self, Method, Bucket, Key=None, Expired=300, headers={}, params={}):
         """获取签名"""
         url = self._conf.uri(bucket=Bucket, path=Key)
         r = Request(Method, url, headers=headers, params=params)
@@ -161,6 +161,7 @@ def get_auth(self, Method, Bucket, Key=None, Expired=10000, headers={}, params={
     def send_request(self, method, url, timeout=30, **kwargs):
         if self._conf._token is not None:
             kwargs['headers']['x-cos-security-token'] = self._conf._token
+        kwargs['headers']['User-Agent'] = 'cos-python-sdk-v5'
         try:
             for j in range(self._retry):
                 if method == 'POST':
@@ -241,10 +242,10 @@ def get_object(self, Bucket, Key, **kwargs):
             response[k] = rt.headers[k]
         return response
 
-    def get_presigned_download_url(self, Bucket, Key, Expired=10000):
+    def get_presigned_download_url(self, Bucket, Key, Expired=300):
         """生成预签名的下载url"""
         url = self._conf.uri(bucket=Bucket, path=Key)
-        sign = self.get_auth(Method='GET', Bucket=Bucket, Key=Key, Expired=10000)
+        sign = self.get_auth(Method='GET', Bucket=Bucket, Key=Key, Expired=300)
         url = url + '?sign=' + urllib.quote(sign)
         return url
 
@@ -335,6 +336,7 @@ def upload_part(self, Bucket, Key, Body, PartNumber, UploadId, **kwargs):
         rt = self.send_request(
                 method='PUT',
                 url=url,
+                headers=headers,
                 auth=CosS3Auth(self._conf._access_id, self._conf._access_key),
                 data=Body)
         response = dict()