The plan layout of the second-line ship lock of the Wan’an Junction comprehensively considers the safety and stability of the adjacent building structure，navigable conditions，construction conditions，demolition and earthwork excavation，etc. The first and second line ship lock axis spacing is 230 m. Through numerical simulation and physical model tests，we analyze and optimize the navigable conditions of the upstream and downstream approach channels，and propose to extend the mooring section of the upstream approach channel of the second-line ship lock and the mooring section shared by the first and second-line ship locks，widen the bottom of upper approach channel and deepen the dredging at the turn，extend the dike between the first-line ship lock and the sluice lock，and adopt the full side discharge method，to improve the navigable conditions of the upstream and downstream approach channels. It can provide reference for the plan layout of ship locks in similar high-head reservoir areas.