To address the problem of limited maritime communication in unmanned ships, this paper proposes a course tracking control method with state/input quantization. The control law of the system is designed based on the backstepping method, and dynamic surface control technology is employed to reduce the computational complexity of the virtual control law. An observer based on the robust exact differentiator (hereinafter referred to as the RED Observer) is employed to estimate uncertainties and external disturbances within a control system. A uniform quantizer is employed to quantize the state variables and control inputs in the control system, respectively, and the quantized state feedback information is solely used for tracking control. The course controller for unmanned ships, based on the RED observer, is designed using quantized state recursion, and the boundedness of the error between quantized and non-quantized variables in the closed-loop control system is proven. Based on Lyapunov stability theory, methods for quantization error calculation and closed-loop system stability assessment are proposed, and the stability of the designed unmanned ship course tracking control system with state and input quantization is proven. Finally, the effectiveness of the proposed control strategy is validated through simulation experiments.