Abstract: Ions irradiation has significant influence on the performance of semiconductor device,thus its working life and reliability in space environment.In this paper the electrical propertie schange of 4H-SiC SBD and its reasons after 1MeV Xe ion irradiation was studied.The influence of Xe ion irradiation with different energy on 4H-SiC SBD was simulated via SRIM software.According to the simulation results,1MeV Xe ion was selected to irradiate 4H-SiC SBD.The experimental results show that the characteristic curve of 4H-SiC SBD changes from Schottky contact to Ohmic contact after irradiation,and a large number of vacancy defects are generated at the interface between metal and semiconductor.These defects reduce the barrier height of the contact interface and increase the tunneling current,which in turn leads to the failure of the rectification characteristics of 4H-SiC SBD.