In order to improve the power absorption and conversion capability of the direct-drive wave energy converters, the direct drive wave power system is studied , the motion equation of the system is analyzed and the mathematical model of the wave power system is established. According to the incident frequency and amplitude of the wave, the optimal power output condition of the system is constructed and the q-axis current reference value is calculated. The sliding mode control algorithm is implemented to track the reference current in real time. Aiming at the wave power system with uncertain disturbance, the robust control is added, so that the generator state can still keep track of the optimal reference in real time. The simulation results show that the proposed robust control strategy can keep track the optimal reference current in real time and maintain the maximum energy absorption despite the presence of uncertain perturbation,improving the robustness of the controlled system.