Hydraulic vertical ship lift with the characteristics of large load,long stroke and variable load,requires a system which should be reliable,stable and safe operation.Therefore,it is necessary to solve the technical problems such as the flow stability of valve control system under load change and the pressure stability under variable flow condition.The modes of proportional commutation valve + pressure compensator,proportional flow valve+pressure compensator have realized the steady and adjustable speed of the leveling oil cylinder and balance oil cylinder with variable load state,and the pressure control of clamping system under the condition of flow change.The modes can make the system smooth and reliable.