In order to adapt to the development of flexible HVDC transmission technology，IGBT modules are becoming smaller，but the internal heating problem of IGBT modules is becoming more and more prominent． Therefore，the issues related to thermal dissipation of IGBT module packages for further exploration have an important guiding significance and practical value． The numerical calculation has its own scope of application and limitation，and the experimental studies are reliable but high cost． At present，ANSYS finite element method to calculate equivalent thermal conductivity of polymeric composites is seldom reported． Then，the method to calculate equivalent thermal conductivity of polymeric composites is studied based on finite element method． The comparison of Maxwell － Eucken equations，experimental results of reference and the obtained results shows the feasibility of this method． Finally，The change regulations of equivalent thermal conductivity of composites considering the factor of filler shape，size，volume fraction，the thermal conductivity of filler particles，particles agglomeration are obtained．