Abstract: In proportional direction valve controlled ship steering system, the proportional direction valve could generate water hammer when it changes direction. Bad affects could be lead to not only the hydraulic steering system but also the ship itself. The model of proportional direction valve controlled ship steering system was created in AMESim. The model and the water hammer simulation result were correct after compared with the test result. Then the current optimization method was used to reduce the water hammer of proportional valve, the optimization result was the parabolic curve. The simulation and the examination results show that the AMESim is fit for the water hammer modeling and simulation of the steering system. The current optimization method can reduce the water hammer significantly.