Zhelin Navigation Junction is located on the main stream of Xin’an River,which is a mountainous river with hydrological characteristics such as rapid rise,quick recession,and short duration.The discharge capacity of mountainous river hubs is crucial to river flood passage safety.Aiming at the challenges of Navigation Junction,such as limited sluice layout space and the need to balance navigation requirements,an optimization study on the hub’s discharge capacity is carried out by means of an integral fixed-bed normal physical model.The impacts of key factors,including riverbed topography,upstream diversion dike of the ship lock,and sluice pier width,on the discharge capacity are analyzed.The results show that the water level difference between the upstream and downstream of the original design fails to meet specification requirements,with uneven flow distribution among sluice holes and weak flow capacity of the right-side holes.By adopting comprehensive measures-optimizing the hub’s designed bottom elevation and pier width,dredging the riverbed near the project area,and adjusting sluice operation modes-the sluice holes’ flow capacity and uniformity are significantly improved,and the maximum water level difference between upstream and downstream is reduced from 0.32 m to 0.20 m.A general layout scheme meeting the hub’s discharge capacity requirements is proposed.The research results provide technical reference for the discharge design and reconstruction of multi-purpose hubs using steel dam gates in mountainous rivers and landscape construction.