In order to improve the heat dissipation performance of IGBT module, a new type of structure unit for Three-dimensional IGBT module packaging which can implement double-sided cooling has been built. In view of the traditional single-sided cooling structure unit of IGBT module and the new type of Three-dimensional structure unit in double-sided cooling IGBT module, a corresponding mathematical model of heat dissipation of the structure has been deduced. The heat dissipation performances of the two models are calculated under the condition of the steady state heat conduction. Moreover, simulation calculation of heat conduction model has been carried out by ANSYS software. Result shows that under the same thermal boundary condition, heat dissipation performance of the double-sided cooling structure unit for Three-dimensional IGBT module package has improved by 47.5% compared with the traditional single-sided cooling structure unit of IGBT module package.