In order to study the thermal damage law of carbon fiber reinforced epoxy composite induced by high power laser, the thermal stress of carbon fiber reinforced epoxy composite with multilayer structure was simulated by COMSOL software. Theoretical analysis and experimental verification were carried out. The temporal and spatial distribution and change of the transient temperature field and stress field of composite materials irradiated by laser with different power densities were obtained. The damage area and morphology of carbon fiber/epoxy resin treated with different laser power density were measured, which was consistent with the trend of numerical simulation results. The results show that, when the temperature of the irradiation center of the target surface is 872K, a temperature plateau appears, that is, the latent heat period of phase change and the latent heat period of reverse phase change, and changes with the laser power density. The laser irradiation target material produced a great axial compressive stress on the upper surface of the carbon fiber. When power density is 293W/cm2, the compressive stress difference is about 1.87MPa; when power density is 3453W/cm2, the compressive stress difference is about 1.42MPa. This result provides a theoretical basis for the research on the thermal damage of carbon fiber/epoxy resin composites caused by high-power lasers.