Abstract: Compared to the traditional light source, high-power LED retains decided advantages, along with wide application prospects. However, heat dissipation has been the major obstacle to the further development of high power LED because of its small volume, heat concentration, and bad resistance to high temperature of the LED chip. Through combining the 3D model design software Pro/Engineer 5.0 heat transfer and fluid analysis software FloEFD PRO12.1, one achieves the model and thermal simulation of 5 W LED heat cooling model. In addition, by applying the method of controlled variable,the radiator fin thickness, curvature and the effect laws of microstructure on the heat dissipation performance have further been explored, therefore enable the structure of radiator get further optimized.