Abstract: Illustrated by the case of Mitsubish IPM（Intelligent Power Module） PS21767,the paper establishes a relatively complete Simplified thermal model and then carried out the research of its working temperature field in the method of finite element analysis with the thermal analysis software——Pro/Mechanica.According to the situation above,the article comes up with an optimization program about IPM thermal performance——using needle-shaped radiators to achieve the rapid dissemination of its exterior heat.This essay also proposes a new package style,which is to encapsulate with mixed plastic resin and aluminum alloy.The thermal analysis shows that this kind of package style has a significant positive effect on IPM chip heat dissemination.