At present, many researchers pay more attention to the thermal-effect of the high energy laser at home and abroad. A few technologies have been demonstrated, such as the water-cooling, the thermoelectric cooler, the phase-change cooling and so on. All of the technologies are induced to minimize the thermal deformation and damage of resonator mirrors and windows in high energy laser. The technologies are compared, the multilayer mirror is disscussed emphatically. The engineering experience verifies this method can meet the requirement of the high power laser system on very small mirror surface deformation. It is very important method for reducing heating effect of the high power laser.