diff --git a/okx/client.py b/okx/client.py
index 9911080..f050f9f 100644
--- a/okx/client.py
+++ b/okx/client.py
@@ -4,6 +4,11 @@ import httpx
 
 from . import consts as c, utils, exceptions
 
+import time
+
+import traceback
+
+from httpx import _client
 
 class Client(object):
 
@@ -16,6 +21,7 @@ class Client(object):
         self.flag = flag
         self.domain = base_api
         self.debug = debug
+        self.request_times = 0
         self.client = httpx.Client(base_url=base_api, http2=True, verify=False, timeout=None)
 
     def _request(self, method, request_path, params):
@@ -38,18 +44,46 @@ class Client(object):
             response = self.client.get(request_path, headers=header)
         elif method == c.POST:
             response = self.client.post(request_path, data=body, headers=header)
-        if not str(response.status_code).startswith('2'):
-            raise exceptions.OkxAPIException(response)
+        self.request_times += 1
+        # print('request times:', self.request_times)
+        if (self.request_times > 512):
+            self.client.close()
+            self.client._state = _client.ClientState.UNOPENED
+            self.request_times = 0
+            # print('close the current tcp connection while request times larger than 512.')
+        return response
+
+    def _request_until_success(self, method, request_path, params):
+        response = ''
+        retry_times = 0
+        while True:
+            try:
+                response = self._request(method, request_path, params)
+                if not str(response.status_code).startswith('2'):
+                    print('response.status_code:', response.status_code)
+                    print('response.json.code:', response.json()['code'])
+                    print('response.json.msg:', response.json()['msg'])
+                    time.sleep(1)
+                    continue
+                break
+            except Exception as e:
+                msg = traceback.format_exc()
+                print(e)
+                retry_times += 1
+                print('http request retry in 1 seconds, retry times:', retry_times)
+                time.sleep(1)
+        # if not str(response.status_code).startswith('2'):
+        #     raise exceptions.OkxAPIException(response)
         return response.json()
 
     def _request_without_params(self, method, request_path):
-        return self._request(method, request_path, {})
+        return self._request_with_params(method, request_path, {})
 
     def _request_with_params(self, method, request_path, params):
-        return self._request(method, request_path, params)
+        return self._request_until_success(method, request_path, params)
 
     def _get_timestamp(self):
-        request_path = c.API_URL + c.SERVER_TIMESTAMP_URL
+        request_path = self.domain + c.SERVER_TIMESTAMP_URL
         response = self.client.get(request_path)
         if response.status_code == 200:
             return response.json()['ts']