The single event effects of power Metal Oxide Semiconductor Field Effect Transistor (MOSFET) are easy to be induced by impacts of heavy ion when they are used in space environment, such as single event burnout and Single Event Gate Rupture(SEGR). The single event effects of domestic new type anti-irradiation power MOSFETs with medium or high voltage(rated voltages are 250 V and 500 V) are studied in this paper. Targeted reinforcement measures are taken and the ability of devices to resist single event effect is significantly improved. Experiment results indicate that the 250 V power MOSFET is irradiated by Bi particles, the drain voltage of safety work reaches 250 V when gate voltage is 0 V; the 500 V power MOSFET is irradiated by Xe particles, the drain voltage of safety work reaches 400 V when gate voltage is 0 V, and the drain voltage of safety work can also reach 400 V when gate voltage is -15 V. The experiment results show that the domestic power MOSFET with medium or high voltage has a good ability to resist single event effect.