The system structure and design principle of the electric drive system for Melbourne high capacity metro train were introduced, and according to the requirement of Melbourne owner, the main circuit was simulated by Matlab. The voltage drop between the two ends of the DC-DC converter’s IGBT, the intermediate DC link voltage Ud, and the harmonic current of grid side and inverter input were analyzed through comparing the voltage and current simulation data under different values of the inherent frequeney which were adjusted by changing the parameters of electric reactor LI. Meanwhile, through building DC-DC converter failure model, input voltage property of traction inverter was assessed in order to provide a reasonable reference for the design of the main circuit electric paramenters.