In　this　paper,　an　experimental　characterization　of　the　behavior　of　commercial　200V/48A　Enhancement-mode　GaN　HEMTs　under　heavy　ion　irradiation　is　presented.　The　damage　caused　by　SEE　may　cumulative　and　permanent,　which　makes　the　drain　leakage　current　gradually　increase.　Regardless　of　whether　SEE　occurs,　the　threshold　voltage　will　shift　after　heavy　ion　irradiation.　The　increase　in　output　capacitance　and　reverse　transfer　capacitance　means　that　the　AlGaN　buffer　layer　is　partially　damaged,　resulting　in　an　increase　in　drain　leakage　current.　©　2021　IEEE