Unlike the water-saving ship locks on canals，the water-saving ship lock of the navigation-power junction in mountainous areas has a large variation of navigable water level and complex terrains on both banks.It faces some difficulties in the layout of water-saving basins，water level classification，and operation mode of the ship lock.For the project in the mountainous area with the navigation structures and the hub separately arranged，this paper studies the layout scheme of the water-saving ship lock.A high water-saving basin and a low one are set on both sides of the ship lock respectively to make full use of the topographic conditions of the project.Given the large variation of upstream navigable water level，it is determined that the ship lock adopts two operation modes of water-saving and non-water-saving，and the upstream critical water level is 214.0 m.In these conditions，the water level classification of the ship lock is calculated and analyzed to determine the elevations of the water-saving basins，and the layout of the filling and emptying system of the water-saving ship lock is put forward.The hydraulic characteristic indexes，the pressures of the culverts near the valves，and the ship berthing conditions in the lock chamber of the ship lock under different operation modes are obtained through the physical model test.Furthermore，the opening and closing modes of the valves are recommended.The results show that the proposed scheme of the water-saving ship lock is reasonable and feasible in hydraulics.