diff --git a/python/paddle/utils/plot.py b/python/paddle/utils/plot.py
index 387c22c99604f59028213d76029727e169f2c6e8..bd6cef1ef2743fb0b4a70fee9324e64cc53d4ea2 100644
--- a/python/paddle/utils/plot.py
+++ b/python/paddle/utils/plot.py
@@ -30,14 +30,14 @@ class PlotData(object):
 
 
 class Ploter(object):
-    '''
+    """
         Plot input data in a 2D graph
         
         Args:
             title: assign the title of input data.
             step: x_axis of the data.
             value: y_axis of the data
-    '''
+    """
 
     def __init__(self, *args):
         self.__args__ = args
@@ -59,7 +59,7 @@ class Ploter(object):
         return self.__disable_plot__ == "True"
 
     def append(self, title, step, value):
-        '''
+        """
             Feed data
         
             Args:
@@ -71,7 +71,7 @@ class Ploter(object):
                 .. code-block:: python
                 plot_curve = Ploter("Curve 1","Curve 2")
                 plot_curve.append(title="Curve 1",step=1,value=1)
-        '''
+        """
         assert isinstance(title, basestring)
         assert self.__plot_data__.has_key(title)
         data = self.__plot_data__[title]
@@ -79,7 +79,7 @@ class Ploter(object):
         data.append(step, value)
 
     def plot(self, path=None):
-        '''
+        """
             Plot data in a 2D graph
             
             Args:
@@ -89,7 +89,7 @@ class Ploter(object):
                 .. code-block:: python
                 plot_curve = Ploter()
                 plot_cure.plot()
-        '''
+        """
         if self.__plot_is_disabled__():
             return