Effects of irradiation dose rates and irradiation temperature are investigated for MOS device under γ-rays. Threshold voltage shift is compared after the MOS devices are radiated at different dose rates and different temperatures. At low dose rate,interface trap formation is affected by the irradiation time and H+ induced in the oxide,the longer the device is radiated and the greater the number of induced H+,the more the interface trap. The effects of temperature on radiation response are related to the time of interface trap formation,it takes more time to form interface trap at low temperatures.