Abstract: In order to study the damage mechanism of high reflectors in high power laser systems, laser damage experiments are carried out on fundamental frequency high reflectors which are widely used in high power laser systems, and then the typical morphologies are compared and analyzed by means of step profiler, scanning electron microscope and surface profiler. The results show that the laser resistance is enhanced because of the SiO2 overlayer; typical damage morphology of the sample without silica overlayer is delamination, which is related to the thermal characteristics of materials, and delamination grows quickly during the subsequent laser irradiation; typical damage morphology of the sample with silica overlayer is plasma ablation with a pit in its center, which is related to the thermal