diff --git a/ppdet/modeling/assigners/atss_assigner.py b/ppdet/modeling/assigners/atss_assigner.py
index e9543c638a456ba7416d1404fdf5c606a94b2d34..550962d8493a6e29de1b0601b994e64d4cd99cc2 100644
--- a/ppdet/modeling/assigners/atss_assigner.py
+++ b/ppdet/modeling/assigners/atss_assigner.py
@@ -124,7 +124,8 @@ class ATSSAssigner(nn.Layer):
 
         # negative batch
         if num_max_boxes == 0:
-            assigned_labels = paddle.full([batch_size, num_anchors], bg_index)
+            assigned_labels = paddle.full(
+                [batch_size, num_anchors], bg_index, dtype=gt_labels.dtype)
             assigned_bboxes = paddle.zeros([batch_size, num_anchors, 4])
             assigned_scores = paddle.zeros(
                 [batch_size, num_anchors, self.num_classes])
diff --git a/ppdet/modeling/assigners/task_aligned_assigner.py b/ppdet/modeling/assigners/task_aligned_assigner.py
index cb0cf1db0fd952ade87738df93c06be878216856..b97923f6c7b3bbf87a83e0eab91ce3358c316069 100644
--- a/ppdet/modeling/assigners/task_aligned_assigner.py
+++ b/ppdet/modeling/assigners/task_aligned_assigner.py
@@ -85,7 +85,8 @@ class TaskAlignedAssigner(nn.Layer):
 
         # negative batch
         if num_max_boxes == 0:
-            assigned_labels = paddle.full([batch_size, num_anchors], bg_index)
+            assigned_labels = paddle.full(
+                [batch_size, num_anchors], bg_index, dtype=gt_labels.dtype)
             assigned_bboxes = paddle.zeros([batch_size, num_anchors, 4])
             assigned_scores = paddle.zeros(
                 [batch_size, num_anchors, num_classes])