In　most　existing　authentication　schemes　users　are　authenticated　by　the　server　one　by　one　which　results　in　lower　efficiency　of　authentication　when　the　number　of　users　is　large.　Aiming　at　the　drawback,　this　paper　propose　an　efficient　trusted　multi-party　authentication　scheme　based　on　threshold　secret　sharing,　the　discrete　logarithm　problem　and　ElGamal　cryptosystem.　Using　(t,n)　threshold　secret　sharing　idea,　the　paper　propose　a　(t,n)　threshold　authentication　scheme　which　can　not　only　simultaneously　authenticate　t　users　satisfying　some　specific　conditions,　but　also　authenticate　new　users　dynamically　by　distributing　a　new　authentication　key　for　the　new　user　which　was　produced　by　t　old　users　and　the　new　user　together.　Finally,　the　security　and　efficiency　of　the　proposed　scheme　are　analyzed.