Abstract: In view of problems of unbalanced capacitor voltage, or big volume and high cost of phase-shifting transformer which provides DC power existed in traditional multilevel converter, the paper proposed a three-phase multilevel converter based on cascaded H-bridge and multi-winding medium-frequency transformer. It introduced circuit structure and working principle of the converter, and analyzed control method of the converter in details. The simulation results show that the converter has stable static characteristics, good dynamic characteristics and little current harmonic.