Due to unmanned surface vehicle (USV) has the features of underactuated and nonlinear, it control problems have always been the difficulty in the field of study and course control is the basis of its various controls. So in this paper, nonlinear USV model is identified and model's validity is verified by rotation test and Z test firstly. Then, for the uncertainty model parameters and random disturbance, backstepping method is employed to design nonlinear course controller. Moreover, in order to eliminate static error, integral term is introduced in control algorithm. Theoretical results on stability analysis indicate that our proposed controller guarantees uniformly ultimate boundedness of all signals of the closed-loop system. Simulation studies with USV model are carried out, and results demonstrate the effectiveness of the proposed control scheme.