To solve the problems of the traditional Sliding Mode Control (SMC) and traditional sliding mode reaching law, such as slow convergence speed, long convergence time and severe chattering in the course control of Unmanned Surface Vehicle (USV), a new Terminal Sliding Mode Control (TSMC) based on new power reaching law is proposed.Firstly, the non-linear function is introduced in the design of sliding hyper-plane based on the idea of TSMC, and a Terminal sliding mode surface is constructed.Under the assumption of improving the dynamic response by the TSMC, a novel power reaching law based on traditional power reaching law is introduced.Then, a new Terminal sliding mode controller is designed based on new reaching law and the TSMC theories.Finally, the Lyapunov stability is proved for the designed control system.The simulation results indicate that:compared with the traditional power reaching law and the exponential reaching law, the designed controller has faster convergence speed and better movement quality.