Power converter is going in the direction of the high power density. Aimed at the trend, a 1200V/300A planar double-side cooling IGBT module has been designed, packaged. Comparing with conventional IGBT module, Parasitic inductance is reduced by 43.26%; Thermal resistance is 26.7% lower; Turn-on time and turn-off time are decreased by 35% and 15.8% respectively; The total power losses are reduced by 8.68%. Therefore the overall performances of the planar double-side cooling IGBT module are superior to the conventional IGBT module. Furthermore, it is possible for IGBT module to improving its current handling capability and power density by designing its packaging structure and packaging process.