IGBT is widely used in high power H-bridge inverter. Traditional IGBT switching loss calculation method is based on the switching energy curve provided by supplier, which is quite different from real switching energy. Therefore, a precise calculation method of high power H-bridge inverter was proposed. The power loss of inverter was composed of IGBT power loss and capacitor power loss, and the IGBT power loss was composed of conduction power loss, turn-on power loss, turn-off power loss and reverse recovery power loss. Calcution method of different power loss was presented and real switching energy curve was obtained using double pulse test resulting of more precise calculation. Finally, a 3.45kVA prototype was build, and the calculated power loss is 210W while the measured power loss was 210W under 1kHz switching frequency at full load. The experimental result verifies the accuracy of the proposed method.