diff --git a/ppdet/modeling/ops.py b/ppdet/modeling/ops.py
index 972fcdf16399422d247a056f364f8ee0a4db3904..5f6b11c4482dd1c99ab45e332a642f24c260b367 100644
--- a/ppdet/modeling/ops.py
+++ b/ppdet/modeling/ops.py
@@ -610,7 +610,7 @@ class MultiClassSoftNMS(object):
             res.set_lod([out_offsets])
             if len(pred_res) == 0:
                 pred_res = np.array([[1]], dtype=np.float32)
-            res.set(np.vstack(pred_res), fluid.CPUPlace())
+            res.set(np.vstack(pred_res).astype(np.float32), fluid.CPUPlace())
             return res
 
         pred_result = create_tmp_var(