With the widely use of power electronic devices in industrial production, such power electronic devices bring negative impedance and nonlinear characteristic, which have adverse effects on the stability of converter system. In this paper, a control strategy is proposed for commonly used three-phase voltage source converter (VSC). The nonlinear disturbance observer (NDO) based sliding mode control (SMC) is used to control the VSC with constant power load to achieve large signal stability of the VSC system. The stability of the control strategy has been analyzed based on Lyapunov method, and the effectiveness of the proposed control method has been verified by Matlab/Simulink simulation.