Abstract: Aiming at the problems such as light intensity change,system oscillation,anti-interference ability and anti-harmonic ability of the photovoltaic grid-connected system,an integral compensation sliding mode control strategy containing state variables is designed for capacitor voltage outer loop to ensure the relative stability of the capacitor voltage without over-harmonic and distortion. A sliding mode controller based improved switching function for the inner loop of grid-connected current to reduce chattering and improve gridconnected effect. Matlab/Simulink platform simulation results verify that the proposed method outperforms the PI and proportional resonance（PR）control strategy,and the proposed method can enhance the global robustness of the grid-connected system,effectively improve the dynamic response speed of the system and the quality of the grid-connected power,and can suppress the harmonic signal of the grid voltage.