diff --git a/icefall/utils.py b/icefall/utils.py
index 9dc718043..8ee62949d 100644
--- a/icefall/utils.py
+++ b/icefall/utils.py
@@ -1,5 +1,6 @@
-# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang
-#                                                    Mingshuang Luo)
+# Copyright      2021  Xiaomi Corp.        (authors: Fangjun Kuang,
+#                                                    Mingshuang Luo,
+#                                                    Zengwei Yao)
 #
 # See ../../LICENSE for clarification regarding multiple authors
 #
diff --git a/test/test_parse_timestamp.py b/test/test_parse_timestamp.py
new file mode 100755
index 000000000..b3f06c54b
--- /dev/null
+++ b/test/test_parse_timestamp.py
@@ -0,0 +1,109 @@
+#!/usr/bin/env python3
+# Copyright      2023  Xiaomi Corp.        (authors: Zengwei Yao)
+#
+# See ../../LICENSE for clarification regarding multiple authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+from pathlib import Path
+
+import k2
+import sentencepiece as spm
+import torch
+
+from icefall.lexicon import Lexicon
+from icefall.utils import parse_bpe_timestamps_and_texts, parse_timestamps_and_texts
+
+ICEFALL_DIR = Path(__file__).resolve().parent.parent
+
+
+def test_parse_bpe_timestamps_and_texts():
+    lang_dir = ICEFALL_DIR / "egs/librispeech/ASR/data/lang_bpe_500"
+    if not lang_dir.is_dir():
+        print(f"{lang_dir} does not exist.")
+        return
+
+    sp = spm.SentencePieceProcessor()
+    sp.load(str(lang_dir / "bpe.model"))
+
+    text = "HELLO WORLD"
+    token_ids = sp.encode(text, out_type=int)
+    # out_type=str: ['_HE', 'LL', 'O', '_WORLD']
+    # out_type=int: [22, 58, 24, 425]
+
+    # [22, 22, 58, 24, 0, 0, 425, 425, 425, 0, 0]
+    labels = (
+        token_ids[0:1] * 2 + token_ids[1:3] + [0] * 2 + token_ids[3:4] * 3 + [0] * 2
+    )
+    # [22, 0, 58, 24, 0, 0, 425, 0, 0, 0, 0]
+    aux_labels = (
+        token_ids[0:1]
+        + [0]
+        + token_ids[1:3]
+        + [0] * 2
+        + token_ids[3:4]
+        + [0] * 4
+        + [-1]
+    )
+
+    fsa = k2.linear_fsa(labels)
+    fsa.aux_labels = torch.tensor(aux_labels).to(torch.int32)
+
+    fsa_vec = k2.create_fsa_vec([fsa])
+
+    utt_index_pairs, utt_words = parse_bpe_timestamps_and_texts(fsa_vec, sp)
+    assert utt_index_pairs[0] == [(0, 3), (6, 8)], utt_index_pairs[0]
+    assert utt_words[0] == ["HELLO", "WORLD"], utt_words[0]
+
+
+def test_parse_timestamps_and_texts():
+    lang_dir = ICEFALL_DIR / "egs/librispeech/ASR/data/lang_bpe_500"
+    if not lang_dir.is_dir():
+        print(f"{lang_dir} does not exist.")
+        return
+
+    lexicon = Lexicon(lang_dir)
+
+    sp = spm.SentencePieceProcessor()
+    sp.load(str(lang_dir / "bpe.model"))
+
+    text = "HELLO WORLD"
+    token_ids = sp.encode(text, out_type=int)
+    # out_type=str: ['_HE', 'LL', 'O', '_WORLD']
+    # out_type=int: [22, 58, 24, 425]
+
+    word_table = lexicon.word_table
+    word_ids = [word_table[s] for s in text.split()]  # [79677, 196937]
+
+    # [22, 22, 58, 24, 0, 0, 425, 425, 425, 0, 0]
+    labels = (
+        token_ids[0:1] * 2 + token_ids[1:3] + [0] * 2 + token_ids[3:4] * 3 + [0] * 2
+    )
+
+    # [[79677], [], [], [], [], [], [196937], [], [], [], [], []]
+    aux_labels = [word_ids[0:1]] + [[]] * 5 + [word_ids[1:2]] + [[]] * 5
+
+    fsa = k2.linear_fsa(labels)
+    fsa.aux_labels = k2.RaggedTensor(aux_labels)
+
+    fsa_vec = k2.create_fsa_vec([fsa, fsa])
+
+    utt_index_pairs, utt_words = parse_timestamps_and_texts(fsa_vec, word_table)
+    assert utt_index_pairs[0] == [(0, 3), (6, 8)], utt_index_pairs[0]
+    assert utt_words[0] == ["HELLO", "WORLD"], utt_words[0]
+
+
+if __name__ == "__main__":
+    test_parse_bpe_timestamps_and_texts()
+    test_parse_timestamps_and_texts()