The technology for multilayer dielectric film of ZrO2-SiO2 has been studied in order to further improve laser damage resistance of reflectors. The coatings for reflecting and laser coupling were developed. The energy density which can be held by them is 160J/cm2 (laser pulse width is 1.2mS at 1.06μm), and the power density is 1.5kW/cm2 (the repetition frequency is 20/S). They can withstand laser irradiation for 3 millions times and not being damaged even in overload test (laser irradiated for 72000 times on the reflector with power density 16kW/cm2).