Abstract: With the rapid development of renewable energy, power conversion system plays a vital role in new energy grid. Aiming at the power unit of power conversion system based on SiC MOSFET, which includes 10 kV high voltage AC module and 750 V low voltage DC module, this paper focuses on the low inductance design and heat dissipation design method of the power unit, and puts forward the overall design scheme of the power unit. By optimizing the structure of the stack bus, the stray inductance of the HVAC module and the LVDC module were reduced to 794 μH and 235 μH respectively, which effectively reduced the turn-off overvoltage of the power unit. Through the thermal simulation study, the heat dissipation scheme of forced air cooling was established, and the required radiator and fan were designed, so that the maximum temperature of the device in the operation process could not exceed 50 ℃. Finally, a prototype of the power unit was built and towing experiments were conducted to verify the effectiveness of the optimization design of the laminated bus structure and the heat dissipation design scheme of the power unit.