diff --git a/README.rst b/README.rst
index 2f2fd04..fd5ea35 100644
--- a/README.rst
+++ b/README.rst
@@ -220,6 +220,24 @@ verify notify from alipay server, example in Pyramid Application
             # this is a invalid notify
 
 
+Single Trade Query
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+..
+
+    单笔交易查询
+
+文档：http://wenku.baidu.com/link?url=WLjyz-H6AlfDLIU7kR4LcVNQgxSTMxX61fW0tDCE8yZbqXflCd0CVFsZaIKbRFDvVLaFlq0Q3wcJ935A7Kw-mRSs0iA4wQu8cLaCe5B8FIq
+
+.. code-block:: python
+
+	import re
+	xml = alipay.single_trade_query(out_trade_no="10000005")
+	res = re.findall('<trade_status>(\S+)</trade_status>', xml) # use RE to find trade_status, xml parsing is more useful, in fact.
+	status = None if not res else res[0]
+	print status # will print out TRADE_SUCCESS when trade is success
+
+
 Example in Pyramid Application
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/src/alipay/__init__.py b/src/alipay/__init__.py
index 9effbea..1eee9eb 100644
--- a/src/alipay/__init__.py
+++ b/src/alipay/__init__.py
@@ -62,10 +62,15 @@ def _check_params(self, params, names):
         if not all(k in params for k in names):
             raise MissingParameter('missing parameters')
 
-    def _build_url(self, service, **kw):
+    def _build_url(self, service, paramnames=None, **kw):
+        '''
+        创建带签名的请求地址，paramnames为需要包含的参数名，用于避免出现过多的参数，默认使用全部参数
+        '''
         params = self.default_params.copy()
         params['service'] = service
         params.update(kw)
+        if paramnames:
+            params = dict([(k, params[k]) for k in paramnames if k in params])
         signkey, signvalue, signdescription = self.sign_tuple
         signmethod = getattr(
             self,
@@ -207,6 +212,18 @@ def check_notify_remotely(self, **kw):
         ).text
         return remote_result == 'true'
 
+    def single_trade_query(self, **kw):
+        '''
+        单笔交易查询,返回xml.
+        out_trade_no或者trade_no参数必须有一个.
+        该接口需要联系支付宝客服签约.
+        '''
+        if 'trade_no' not in kw and 'out_trade_no' not in kw:
+            raise MissingParameter('missing parameters')
+        url = self._build_url('single_trade_query', paramnames=['service', 'partner', '_input_charset', 'sign', 'sign_type', 'trade_no', 'out_trade_no'], **kw)
+        remote_result = requests.get(url, headers={'connection': 'close'}).text
+        return remote_result
+
 '''Wap支付接口'''
 
 
@@ -257,7 +274,7 @@ def create_direct_pay_by_user_url(self, **kw):
                 raise TokenAuthorizationError(unquote(params['res_error'][0]))
         else:
             token = kw['token']
-        params = {'req_data': self._xmlnode %
+        params = {'req_data': self._xmlnode % 
                   (self.AUTH_ROOT_NODE,
                    (self._xmlnode % ('request_token', token, 'request_token')),
                    self.AUTH_ROOT_NODE)}
diff --git a/src/alipay/tests.py b/src/alipay/tests.py
index 5ceeb49..26d7c31 100644
--- a/src/alipay/tests.py
+++ b/src/alipay/tests.py
@@ -196,3 +196,10 @@ def test_wap_notifyurl(self):
                   'sign': '1f0a524dc51ed5bfc7ee2bac62e39534'}
         rt = self.wapalipay.verify_notify(**params)
         self.assertFalse(rt)
+
+    def test_single_trade_query(self):
+        ''' single_trade_query will response a ILLEGAL_PARTNER error xml document, like:
+        <?xml version="1.0" encoding="utf-8"?>
+        <alipay><is_success>F</is_success><error>ILLEGAL_PARTNER</error></alipay>
+        '''
+        self.assertIn('ILLEGAL_PARTNER', self.alipay.single_trade_query(out_trade_no='2015102012'))
\ No newline at end of file