diff --git a/astrbot/core/provider/sources/dify_source.py b/astrbot/core/provider/sources/dify_source.py
index e6f345741..9539227fe 100644
--- a/astrbot/core/provider/sources/dify_source.py
+++ b/astrbot/core/provider/sources/dify_source.py
@@ -100,6 +100,7 @@ class ProviderDify(Provider):
         session_vars = sp.get("session_variables", {})
         session_var = session_vars.get(session_id, {})
         payload_vars.update(session_var)
+        payload_vars["system_prompt"] = system_prompt
 
         try:
             match self.api_type: