Abstract:The size of pin fins details feature is very small, which limits the size of the grid and restricts the complete simulation analysis of the water-cooled radiator. The method that calculating the fluid field in the flow field first, then using symmetry method to establish thermal simulation model for the heat dissipating performance was presented. The highest temperature of the chips and IGBT moudle mounting surface temperature changing were obtained. The comparative analysis of three branch flow distributions situation with and without pressure relief slot were also stuided. The results show that the relief slot can effectively adjust the pressure and flow rate of three branch, making three branch flow basically equal. The research methods can be used to effectively solve and implement simulation calculation of complicated problem. The research results can provide guidance for IGBT water cooled radiator design work.