diff --git a/data_juicer/format/formatter.py b/data_juicer/format/formatter.py
index 86ea481db..c47ad2414 100644
--- a/data_juicer/format/formatter.py
+++ b/data_juicer/format/formatter.py
@@ -208,11 +208,16 @@ def non_empty_text(sample, target_keys):
 
     # 3. convert relative paths to absolute paths
     if global_cfg:
+        ds_dir = global_cfg.dataset_dir
+        image_key = global_cfg.image_key
+
+        if image_key not in dataset.features:
+            # no image path list in dataset, no need to convert
+            return dataset
+
         logger.info('Converting relative paths in the dataset to their '
                     'absolute version. (Based on the directory of input '
                     'dataset file)')
-        ds_dir = global_cfg.dataset_dir
-        image_key = global_cfg.image_key
 
         # function to convert relative paths to absolute paths
         def rel2abs(sample, path_keys, dataset_dir):
diff --git a/data_juicer/ops/mapper/chinese_convert_mapper.py b/data_juicer/ops/mapper/chinese_convert_mapper.py
index 5f55dedd3..fc321094c 100644
--- a/data_juicer/ops/mapper/chinese_convert_mapper.py
+++ b/data_juicer/ops/mapper/chinese_convert_mapper.py
@@ -5,7 +5,12 @@
 OP_NAME = 'chinese_convert_mapper'
 
 with AvailabilityChecking(['opencc'], OP_NAME):
-    import opencc
+    import opencc  # noqa: F401
+
+
+def prepare_converter(mode):
+    global OPENCC_CONVERTER
+    OPENCC_CONVERTER = opencc.OpenCC(mode + '.json')
 
 
 @OPERATORS.register_module(OP_NAME)
@@ -44,9 +49,9 @@ def __init__(self, mode: str = 's2t', *args, **kwargs):
         ]
         assert mode in mode_list, 'Please make sure mode is one of {}'.format(
             mode_list)
-        self.converter = opencc.OpenCC(mode + '.json')
+        prepare_converter(mode)
 
     def process(self, sample):
 
-        sample[self.text_key] = self.converter.convert(sample[self.text_key])
+        sample[self.text_key] = OPENCC_CONVERTER.convert(sample[self.text_key])
         return sample