diff --git a/src/llamafactory/extras/constants.py b/src/llamafactory/extras/constants.py
index c6ddd61b..7c58e2c5 100644
--- a/src/llamafactory/extras/constants.py
+++ b/src/llamafactory/extras/constants.py
@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import os
 from collections import OrderedDict, defaultdict
 from enum import Enum
 from typing import Dict, Optional
@@ -47,7 +48,7 @@ FILEEXT2TYPE = {
 
 IGNORE_INDEX = -100
 
-IMAGE_PLACEHOLDER = "<image>"
+IMAGE_PLACEHOLDER = os.environ.get("IMAGE_PLACEHOLDER", "<image>")
 
 LAYERNORM_NAMES = {"norm", "ln"}
 
@@ -95,7 +96,7 @@ SUPPORTED_CLASS_FOR_BLOCK_DIAG_ATTN = {
 
 SUPPORTED_CLASS_FOR_S2ATTN = {"llama"}
 
-VIDEO_PLACEHOLDER = "<video>"
+VIDEO_PLACEHOLDER = os.environ.get("VIDEO_PLACEHOLDER", "<video>")
 
 V_HEAD_WEIGHTS_NAME = "value_head.bin"