Abstract: The traditional carrier phase-shifting modulation method of cascade high-voltage inverter has the problems of large switching loss and low utilization rate of DC voltage, and modulation method based on combination of carrier phase-shifting and vector control has problems of large calculated amount, complex computation and difficult to achieve. In allusion to the problems mentioned above, an optimization control method of cascade multi-level inverter was proposed, namely zero-sequence component method of modulation signal and two-phase control method. The method uses idea of freedom degrees of combination control, and can improve DC voltage utilization rate and reduce the switching losses through injecting zero sequence component and DC component to modulation wave. The simulation result shows that the method is feasible.