“In the field of radiation resistance applications, the excellent performance of gallium nitride devices has attracted much attention. We conducted 5 MeV proton irradiation experiments on GaN HEMT devices with enhanced Cascoe cascade structure and P-GaN gate structure, analyzed the degradation law of device electrical characteristics, and clarified the damage mechanism of proton irradiation effect. The research results have certain reference value for the reinforcement design of GaN power devices and the selection of aerospace application devices.”