The　objective　of　this　study　was　to　address　the　deviation　of　electrical　parameters,　which　is　caused　by　the　self-temperature　rise　effect　of　power　devices　in　electrical　testing　processes.　The　pulse　width　and　amplitude　of　the　device　test　were　considered　as　the　research　object.　The　three-dimensional　variation　of　the　power,　junction　temperature,　and　pulse　width　of　semiconductor　power　devices　were　investigated　using　the　principle　of　electrical　temperature　measurement,　and　the　three-dimensional　variation　surfaces　of　the　power,　junction　temperature,　and　pulse　width　were　established.　A　method　for　selecting　the　pulse　width　and　amplitude　of　the　test　to　avoid　the　self-temperature　rise　of　the　power　device　is　proposed.　This　method　uses　cutting　projection　to　obtain　the　characteristic　curve　of　the　pulse　width　and　power　change,　and　selects　an　appropriate　two-dimensional　region　of　the　pulse　width　and　power　to　avoid　the　self-temperature　rise　of　the　power　device.　Moreover,　the　proposed　method　can　be　used　as　a　reference　when　selecting　a　pulse　test　method.　©　Published　under　licence　by　IOP　Publishing　Ltd.