Aiming　at　the　weakness　of　existing　schemes,　a　new　threshold　signature　scheme　to　withstand　the　conspiracy　attack　is　proposed　in　this　paper.　In　this　scheme,　any　subset　of　t　or　more　than　t　members　of　the　group　can　execute　a　valid　threshold　signature　on　behalf　of　the　whole　but　can＇t　construct　legal　group　signature　through　giving　two　specific　equations　contained　each　other,　so　this　scheme　can　not　only　withstand　conspiracy　attacks　effectively,　but　also　provide　traceability　under　the　premise　of　group　signature　anonymity.　In　addition,　a　new　conspiracy　attack　method　is　designed,　which　was　adopted　to　test　the　existing　schemes　and　the　new　scheme　of　this　paper,　the　result　shows　new　scheme　has　higher　security　than　existing　ones.　©　2010　IEEE.