Abstract: The basic theory of the temperature field of optical thin films is given.The temperature field distribution of dielectric thin films irradiated by 10.6μm CO2 lasers has been simulated numerically and analyzed theoretically using alternating direction-implicit technique.Using the Shack-Hartmann wavefront sensor,the thermal distortion of the substrate,the single-layer dielectric thin films with different thickness,and the multi-layer dielectric thin films with different multilayer thin films(YbF3/ZnSe)irradiated by CO2 laser are studied experimentally.It can be shown that the temperature field distribution of thin film coatings irradiated by lasers deperds on the field distribution,power and irradiating time of lasers.For the 10.6μm laser,Ge is the most suitable substrate material.