The variation of peak temperature of metal materials irradiated by continuous wave (CW) laser is studied in this paper. We established a finite element model of metal materials irradiated by CW laser. The variation of peak temperature of aluminum alloy circular plates irradiated by CW laser is studied by simulation analysis method. By analyzing the simulation results under different conditions, such as beam drift, spot diffusion, air convection and material surface oxidation, the effects of various factors on the peak temperature of laser-irradiated materials are given, and the influence of latent heat of phase change on temperature rise is analyzed by using the method of equivalent material specific heat capacity. Finally, according to various conditions, the change of peak temperature of aluminum alloy irradiated by CW laser is given, and the damage of aluminum alloy is analyzed.