diff --git a/fastNLP/io/data_loader/matching.py b/fastNLP/io/data_loader/matching.py
index 1cde950f..3d131bcb 100644
--- a/fastNLP/io/data_loader/matching.py
+++ b/fastNLP/io/data_loader/matching.py
@@ -4,9 +4,9 @@ from typing import Union, Dict
 
 from ...core.const import Const
 from ...core.vocabulary import Vocabulary
-from ...io.base_loader import DataInfo, DataSetLoader
-from ...io.dataset_loader import JsonLoader, CSVLoader
-from ...io.file_utils import _get_base_url, cached_path, PRETRAINED_BERT_MODEL_DIR
+from ..base_loader import DataInfo, DataSetLoader
+from ..dataset_loader import JsonLoader, CSVLoader
+from ..file_utils import _get_base_url, cached_path, PRETRAINED_BERT_MODEL_DIR
 from ...modules.encoder._bert import BertTokenizer
 
 
diff --git a/fastNLP/io/dataset_loader.py b/fastNLP/io/dataset_loader.py
index 26edd8bd..2881e6e9 100644
--- a/fastNLP/io/dataset_loader.py
+++ b/fastNLP/io/dataset_loader.py
@@ -16,8 +16,6 @@ __all__ = [
     'CSVLoader',
     'JsonLoader',
     'ConllLoader',
-    'SNLILoader',
-    'SSTLoader',
     'PeopleDailyCorpusLoader',
     'Conll2003Loader',
 ]
@@ -30,7 +28,6 @@ from ..core.dataset import DataSet
 from ..core.instance import Instance
 from .file_reader import _read_csv, _read_json, _read_conll
 from .base_loader import DataSetLoader, DataInfo
-from .data_loader.sst import SSTLoader
 from ..core.const import Const
 from ..modules.encoder._bert import BertTokenizer
 
@@ -111,7 +108,7 @@ class PeopleDailyCorpusLoader(DataSetLoader):
             else:
                 instance = Instance(words=sent_words)
             data_set.append(instance)
-        data_set.apply(lambda ins: len(ins["words"]), new_field_name="seq_len")
+        data_set.apply(lambda ins: len(ins[Const.INPUT]), new_field_name=Const.INPUT_LEN)
         return data_set
 
 
diff --git a/test/io/test_dataset_loader.py b/test/io/test_dataset_loader.py
index b091339e..09ad8c83 100644
--- a/test/io/test_dataset_loader.py
+++ b/test/io/test_dataset_loader.py
@@ -1,7 +1,7 @@
 import unittest
 import os
 from fastNLP.io import Conll2003Loader, PeopleDailyCorpusLoader, CSVLoader, JsonLoader
-from fastNLP.io.dataset_loader import SSTLoader, SNLILoader
+from fastNLP.io.data_loader import SSTLoader, SNLILoader
 from reproduction.text_classification.data.yelpLoader import yelpLoader
 
 
@@ -61,3 +61,12 @@ class TestDatasetLoader(unittest.TestCase):
         print(info.vocabs)
         print(info.datasets)
         os.remove(train), os.remove(test)
+
+    def test_import(self):
+        import fastNLP
+        from fastNLP.io import SNLILoader
+        ds = SNLILoader().process('test/data_for_tests/sample_snli.jsonl', to_lower=True,
+                                  get_index=True, seq_len_type='seq_len')
+        assert 'train' in ds.datasets
+        assert len(ds.datasets) == 1
+        assert len(ds.datasets['train']) == 3