diff --git a/src/llamafactory/data/loader.py b/src/llamafactory/data/loader.py
index 322eefa0..fa5b12c5 100644
--- a/src/llamafactory/data/loader.py
+++ b/src/llamafactory/data/loader.py
@@ -108,7 +108,13 @@ def load_single_dataset(
         dataset = dataset.to_iterable_dataset()  # TODO: add num shards parameter
 
     if dataset_attr.num_samples is not None and not data_args.streaming:
-        indexes = np.random.permutation(len(dataset))[: dataset_attr.num_samples]
+        target_num = dataset_attr.num_samples
+        indexes = np.random.permutation(len(dataset))[:target_num]
+        target_num -= len(indexes)
+        if target_num > 0:
+            expand_indexes = np.random.choice(len(dataset), target_num)
+            indexes = np.concatenate((indexes, expand_indexes), axis=0)
+
         dataset = dataset.select(indexes)
         logger.info("Sampled {} examples from dataset {}.".format(dataset_attr.num_samples, dataset_attr))