The　channel　temperature　dependence　of　the　drain　current　transient　responses　of　AlGaN/GaN　HEMTs　are　studied　by　experimental　measurement　and　simulation.　The　relationship　between　the　channel　transient　temperature　rise　and　drain　current　drop　are　discussed　in　detail.　The　results　show　that　the　temperature　is　the　main　factor　for　the　drain　current　decrease.　Two　shoulders　exist　on　the　transient　drain　current　response　curve.　The　time　for　the　shoulders　appear　depends　on　the　thermal　time　constant,　which　is　10　ms　and　60　s　in　the　case.　The　decrease　of　transient　drain　current　and　transient　temperature　rise　have　a　complementary　relationship.　Furthermore,　the　measurement　results　are　found　to　be　consistent　with　the　electro-thermal　simulation　results.