In this paper, silicon carbide field effect transistor device is taken as a research object, and the cobalt source irradiation experiment is conducted under different voltages and different temperatures and the annealing experiment is also performed after irradiation. The semiconductor parameter analyzer is used to test the direct current (DC) parameters of the device, and the changes in the radiation sensitive parameters of the device in the irradiation and annealing process are studied. The reasons for the influence of voltage and temperature on the radiation degradation of the device are analyzed, and the annealing recovery is also explored. The results show that the oxide trapped charge induced by irradiation is the main reason for the degradation of the electrical parameters of the silicon carbide field effect transistor device. The voltage and temperature can affect the final yield of the oxide trapped charge, which causes the device to produce the difference in the degree of degradation after irradiation at different voltages and different temperatures; in the annealing process, due to the annealing of the tunneling of oxide trapped charges, the electrical performance of the device can be restored partially.