Abstract: Based on CFD software FLUENT, the secondary development was conducted targeting at a full solution for numerical simulation of green water problem. This solution consists of dynamic mesh, numerical wave tank integrated with piston type wavemaker and a dissipation zone, an automatic strategy for calculating ship motion, water surface capturing scheme——VOF method, high efficiency mesh plan and an accurate timestep. The solution was put into use on a freely moving ship in head wave. During the simulation, motion of the ship was calculated; and both the evolution process of green water and the impact load of green water were recorded.