Abstract: In this paper, a new method is proposed to effectively lower the high temperature, smooth the thermal stress and reduce the thermal deformation of mirrors in high power laser systems utilizing functionally graded materials (FGMs). Two kinds of laser source are discussed at the same time. One is the doughnut-shaped laser, and the other is the Gaussian-distributed laser. Numerical results from finite element analysis show that the thermal deformation of silicon and copper mirrors can be much reduced in magnitude, and the temperature rise is also lowered obviously by this means. The effects of slope regulation of the functions for representation of thermophysical and mechanical properties on thermal deformation of mirrors are discussed to meet the requirement of optimum design and manufacture