A　novel　3-D　IGBT　thermal　model　is　implemented.　The　temperature　distribution　in　different　conditions　was　analyzed　by　using　finite　element　thermal　analysis　software　ANSYS.　Simulation　results　under　the　conditions　of　different　heat　source　spacing,　respectively　5μm,　10μm　and　15μm,　show　that　increasing　the　heat　source　spacing　appropriately　can　reduce　the　thermal　coupling　effect,　thereby　reducing　the　peak　temperature　of　IGBT.　Temperature　dependent　thermal　conductivity　of　Si　was　considered　during　simulation,　the　results　indicate　the　peak　temperature　rise　4.8K　in　the　same　power.　The　results　of　thermal　resistance　obtained　by　simulation　are　in　agreement　with　the　measured　value.