Heat dissipation is one of the bottlenecks which affect the life time, luminous efficiency and reliability of LED devices.This is also the reason reson restrict the development of high power LED devices.Thermal analysis was carried out by combining T3ster thermal resistance tester with ANSYS simulation.The thermal resistance and junction temp erature performances of the three kinds of thermal interface materials(80Au 20Sn,solder paste and silver paste) of HP-LED are compared first,then the interface material thermal conduc tivity,the interface material thickness and the contact ratio between the interf ace material with the chip are simulated respectively.The results show that the rinterface thermal resistance plays an important role on the total thermal resis tance of LED devices,and is one of the main factors which affect the junction te mperature of LED.The simulated results show that the interface material thermal conductivity,the interface material thickness and the contact ratio of the inter face material all can influence of the HP-LED junction temperature.So these thr ee parameters should be made an overall consideration for HP-LED thermal design .