The inertial navigation system (INS) of ships switches between two modes of undamped navigation and horizontal-damped navigation according to the state of motion, during which the system error caused by the acceleration of the ship and the overshoot error resulted from the frequent switches between two modes may degrade the dynamic performance of the INS.Considering the limitations of traditional damping method, the adaptive control method was applied to design a level damping network of platform inertial navigation.The damping network parameters were changed adaptively according to the acceleration, thus to make the system error minimum.And a method for restraining the overshoot error caused by mode switching was also proposed.Theoretical analysis and simulation result shows that the method can improve the dynamic performance of the INS effectively.