Abstract: Considering the nonlinear characteristics, modeling uncertainties and external disturbances such as wind, wave and flow in ship motion systems, an adaptive fuzzy sliding mode control (AFSMC) technology is presented to solve the ship course control problem. The fuzzy logic system is used to approximate the unknown system function and the adaptive fuzzy sliding mode controller is designed by combining sliding mode control technology with adaptive fuzzy control technology. The chattering problem of sliding mode control is relieved by adopting PI (proportional-integral) control instead of sliding mode control switching items within the boundary layer. Based on the Lyapunov function, it is theoretically proved that the controller makes all signals in the system of ship motion uniformly bounded, and using Barbalat's lemma, the tracking errors converge to zero. Simulation experiments on the course keeping and change in the presence of parameter perturbation and environment disturbances are conducted, and similar output responses with those under no perturbation and no interference circumstances by the controller based on AFSMC are obtained. The experiment results show that the proposed controller can handle system uncertainties and external disturbances effectively, and has superior controlling performance and strong robustness.