GaN High-Electron-Mobility Transistors(HEMTs) devices bear the characteristics of high frequency resistance, high temperature resistance, high power and radiation resistance, which have broad application prospects in radiation environments such as nuclear reactors, cosmic detection and other radiation environments. Therefore, Stopping and Range of Ions in Matter(SRIM) is employed to simulate the effect of 1.8 MeV proton radiation on the conventional depletion device with different AlGaN barriers, and to observe the change law of vacancy density with depth. Under the optimal AlGaN barrier thickness, the MIS-HEMT devices of five different gate oxygen layer materials are simulated and compared. It is found that the material of Aluminum Nitride(AlN) gate oxygen layer bears relatively good radiation resistance.