This paper proposes a cascade-based control algorithm for distributed consensus tracking of multi-underactuated surface vessels(USVs) system.The presented control algorithm can be divided into two parts.The first part is a distributed control estimator under sampled interactions,which is used to estimate the leader's trajectory.The second part is the local control law,driving each USV to track the obtained estimated trajectory by invoking sliding mode control combined with the radical basis function neural network in terms of the underactuated feature,environmental disturbance and model uncertainties.Besides,in order to solve the presented tracking problem,several sufficient conditions are obtained via Lyapunov theory and cascade system theory to ensure that the position states of all USVs converge to the desired position.The simulation results show the correctness and effectiveness of the proposed theorem.