diff --git a/backend/app/api/simulation.py b/backend/app/api/simulation.py
index 7de5bed..3a91391 100644
--- a/backend/app/api/simulation.py
+++ b/backend/app/api/simulation.py
@@ -4,6 +4,7 @@ Step2: Zep实体读取与过滤、OASIS模拟准备与运行（全程自动化
 """
 
 import os
+import json
 import traceback
 from flask import request, jsonify, send_file