diff --git a/game-server/app/servers/battle/handler/guildRefineHandler.ts b/game-server/app/servers/battle/handler/guildRefineHandler.ts
index c2ff42634..eae648e3b 100644
--- a/game-server/app/servers/battle/handler/guildRefineHandler.ts
+++ b/game-server/app/servers/battle/handler/guildRefineHandler.ts
@@ -133,7 +133,7 @@ export class GuildRefineHandler {
         if (!result) 
             return resResult(STATUS.ROLE_MATERIAL_NOT_ENOUGH);   
         scienceTree.assistRoleIds.push(roleId);
-        scienceTree.endTime -= scienceTree.endTime - ARMY.ARMY_DEVELOPMENT_SPEED * 60;
+        scienceTree.endTime = scienceTree.endTime - ARMY.ARMY_DEVELOPMENT_SPEED * 60;
         let { scienceTrees } = await GuildRefineModel.updateRefine(code, { scienceTrees: guildRefine.scienceTrees })
         res.releaseCallback();
         return resResult(STATUS.SUCCESS, { scienceTrees });