Abstract: In order to overcome the shortcoming of long time interval between two shoots in the high-energy laser by using phase change material(PCM) cooled mirror,a novel semiconductor-cooled composite phase chang silicon mirror is presented in this paper.Thermal process of laser radiation of solid silicon mirror,PCM and semiconductor-cooled mirror is simulated by ANSYS finite element program. From the largest temperature-time curves there can be seen that semiconductor-cooled composite phase chang silicon mirror can restore the temperature of mirror and elastic deformation to their start for 5s in the 25W of refrigerating output under 20℃ of environment temperature and 100W of net absorption heat quantity.