Aiming at the problem of poor symmetry of output AC voltage when traditional three-phase three-leg inverters drive unbalanced loads, the control strategy of three-phase four-leg inverters is studied and analyzed. The first three legs adopt positive and negative sequence control strategy of output voltage, and the fourth legs use neutral current to track the negative sum of load current to control separately, which can effectively improve the universality of three-phase four-leg inverter and reduce its control difficulty. The simulation model of MATLAB is built to verify the rationality and feasibility of the control strategy and realize the ability to drive unbalanced load.