Direct　current　(DC)　reverse　step　voltage　stress　is　applied　on　the　gate　of　an　AlGaN/GaN　high-electron　mobility　transistor　(HEMT).　Experiments　show　that　parameters　degenerate　under　stress.　Large-signal　parasitic　source/drain　resistance　(R-S/R-D)　and　gate-source　forward　I-V　characteristics　are　recoverable　after　breakdown　of　the　device　under　test　(DUT).　Electrons　trapped　by　both　the　AlGaN　barrier　trap　and　the　surface　state　under　stress　lead　to　this　phenomenon,　and　surface　state　recovery　is　the　major　reason　for　the　recovery　of　device　parameters.