diff --git a/python/paddle/v2/fluid/tests/test_prior_box_op.py b/python/paddle/v2/fluid/tests/test_prior_box_op.py
index 25dfc4307c05dc40594e1b590dd4e825bbfd77ff..a6c21af49f63269720156ec833c94688d0e3230e 100644
--- a/python/paddle/v2/fluid/tests/test_prior_box_op.py
+++ b/python/paddle/v2/fluid/tests/test_prior_box_op.py
@@ -65,9 +65,9 @@ class TestPriorBoxOp(OpTest):
         self.batch_size = 10
 
         self.min_sizes = [2, 4]
-        self.min_sizes = np.array(self.min_sizes).astype('float32')
+        self.min_sizes = np.array(self.min_sizes).astype('float32').tolist()
         self.max_sizes = [5, 10]
-        self.max_sizes = np.array(self.max_sizes).astype('float32')
+        self.max_sizes = np.array(self.max_sizes).astype('float32').tolist()
         self.aspect_ratios = [2.0, 3.0]
         self.flip = True
         self.real_aspect_ratios = [1, 2.0, 1.0 / 2.0, 3.0, 1.0 / 3.0]