diff --git a/fastNLP/core/dataset.py b/fastNLP/core/dataset.py
index f25e2cfd..4b995c94 100644
--- a/fastNLP/core/dataset.py
+++ b/fastNLP/core/dataset.py
@@ -288,6 +288,8 @@ class DataSet(object):
             extra_param['is_input'] = kwargs['is_input']
         if 'is_target' in kwargs:
             extra_param['is_target'] = kwargs['is_target']
+        if 'ignore_type' in kwargs:
+            extra_param['ignore_type'] = kwargs['ignore_type']
         if new_field_name is not None:
             if new_field_name in self.field_arrays:
                 # overwrite the field, keep same attributes
@@ -296,11 +298,14 @@ class DataSet(object):
                     extra_param['is_input'] = old_field.is_input
                 if 'is_target' not in extra_param:
                     extra_param['is_target'] = old_field.is_target
+                if 'ignore_type' not in extra_param:
+                    extra_param['ignore_type'] = old_field.ignore_type
                 self.add_field(name=new_field_name, fields=results, is_input=extra_param["is_input"],
-                               is_target=extra_param["is_target"])
+                               is_target=extra_param["is_target"], ignore_type=extra_param['ignore_type'])
             else:
                 self.add_field(name=new_field_name, fields=results, is_input=extra_param.get("is_input", None),
-                               is_target=extra_param.get("is_target", None))
+                               is_target=extra_param.get("is_target", None),
+                               ignore_type=extra_param.get("ignore_type", False))
         else:
             return results
 
diff --git a/fastNLP/core/fieldarray.py b/fastNLP/core/fieldarray.py
index 148dfc6c..1d95dbeb 100644
--- a/fastNLP/core/fieldarray.py
+++ b/fastNLP/core/fieldarray.py
@@ -83,6 +83,8 @@ class AutoPadder(PadderBase):
             array = np.full((len(contents), max_len), self.pad_val, dtype=field_ele_dtype)
             for i, content in enumerate(contents):
                 array[i][:len(content)] = content
+        elif field_ele_dtype is None:
+            array = contents  # 当ignore_type=True时，直接返回contents
         else:  # should only be str
             array = np.array([content for content in contents])
         return array
diff --git a/test/core/test_dataset.py b/test/core/test_dataset.py
index 231fedd0..eb4c97e8 100644
--- a/test/core/test_dataset.py
+++ b/test/core/test_dataset.py
@@ -120,6 +120,9 @@ class TestDataSetMethods(unittest.TestCase):
         self.assertTrue(isinstance(res, list) and len(res) > 0)
         self.assertTrue(res[0], 4)
 
+        ds.apply(lambda ins: (len(ins["x"]), "hahaha"), new_field_name="k", ignore_type=True)
+        # expect no exception raised
+
     def test_drop(self):
         ds = DataSet({"x": [[1, 2, 3, 4]] * 40, "y": [[5, 6], [7, 8, 9, 0]] * 20})
         ds.drop(lambda ins: len(ins["y"]) < 3)
@@ -170,7 +173,7 @@ class TestDataSetMethods(unittest.TestCase):
         dataset.apply(split_sent, new_field_name='words', is_input=True)
         # print(dataset)
 
-    def test_add_field(self):
+    def test_add_field_v2(self):
         ds = DataSet({"x": [3, 4]})
         ds.add_field('y', [['hello', 'world'], ['this', 'is', 'a', 'test']], is_input=True, is_target=True)
         # ds.apply(lambda x:[x['x']]*3, is_input=True, is_target=True, new_field_name='y')
diff --git a/test/core/test_fieldarray.py b/test/core/test_fieldarray.py
index e3595f9a..ff1a8314 100644
--- a/test/core/test_fieldarray.py
+++ b/test/core/test_fieldarray.py
@@ -222,4 +222,14 @@ class TestPadder(unittest.TestCase):
             [[[1, 2, 3, -100, -100], [4, 5, -100, -100, -100], [7, 8, 9, 10, -100]],
              [[1, -100, -100, -100, -100], [-100, -100, -100, -100, -100], [-100, -100, -100, -100, -100]]],
             padder(contents, None, np.int64).tolist()
-        )
\ No newline at end of file
+        )
+
+    def test_None_dtype(self):
+        from fastNLP.core.fieldarray import AutoPadder
+        padder = AutoPadder()
+        content = [
+            [[1, 2, 3], [4, 5], [7, 8, 9, 10]],
+            [[1]]
+        ]
+        ans = padder(content, None, None)
+        self.assertListEqual(content, ans)