To avoid the ship collision automatically, the domain concept of navigation obstruction and the theory of dynamic boundary are employed to establish the ship domain model and dynamic static obstacles model. Then, the ship collision risk quantification model is deduced by considering the factors of shallow bottom, quay, wind and current. Observing from the ship, the ship automatic collision avoidance in restricted waters is modeled based on the operating performance of the ship and the collision risk of the static obstacles and dynamic target, and the current environmental factors, and combining the potential field theory and the theory of ship collision avoidance, ship domain bound theory. Numerical simulation results show that the ship controlled by the automatic collision avoidance model could sail safely in restricted waters regions, and the limitations of traditional potential field model were solved.