To solve the problem of trajectory tracking of fully-actuated Unmanned Surface Vessels (USV),a dual-layer control method combining Model Predictive Control(MPC) with Integral Sliding Mode Control(ISMC) is proposed.Firstly,as for the kinematics model of the USV system,a model predictive controller is designed to obtain the desired velocity signal satisfying the constraints according to the desired trajectory.As for the dynamics model,an integral sliding mode controller is designed to track the desired signal in the presence of external disturbances,which improves the robustness of the system.A nonlinear disturbance observer is designed to estimate the external disturbance and compensate for the external disturbance during the design of the control law.Finally,the stability of the system is proved by the Lyapunov method.Numerical simulation proves that the combination of the two can effectively achieve the trajectory tracking of the fully-actuated USV.