diff --git a/python/paddle/reader/creator.py b/python/paddle/reader/creator.py
index 5c840f94b52f16a01521322c3d0480beb337ada1..5a91bb0b8ef6d1874737386897f6c555eaec18d4 100644
--- a/python/paddle/reader/creator.py
+++ b/python/paddle/reader/creator.py
@@ -17,8 +17,9 @@ __all__ = ['np_array', 'text_file']
 
 def np_array(x):
     """
-    Creates a data reader from numpy array.
-    The highest dimension will be treated as batch dimension to iterate on.
+    Creates a reader that yields elements of x, if it is a
+    numpy vector. Or rows of x, if it is a numpy matrix.
+    Or any sub-hyperplane indexed by the highest dimension.
 
     :param x: the numpy array to create reader from.
     :returns: data reader created from x.