The first-phase water storage target of the Nianpanshan hub has been achieved.In response to the problems existed in the proposed 265 m design scheme of the second-line ship lock at Nianpanshan hub,such as the large angle between the upstream and downstream diversion channels and the main channel,the poor navigation water conditions of the second-line ship lock,and shallowing of the channel and insufficient navigation width during the dry season due to the adjustment of the riverbed downstream of the dam,an optimization test study of the second-level ship lock scheme is carried out through tests of the navigation water conditions of the ship lock and self-propelled ship models.Engineering measures are proposed,such as building a 430 m guide dike upstream of the proposed second-line ship lock,conducting double-digging and trumpet-shaped slot dredging downstream,and blocking the left branch during the low-water period when the downstream channel is being rectified.After the implementation of the optimization scheme,the navigation conditions upstream and downstream of the existing first-line ship lock are improved,and the navigation flow conditions of the proposed second-line ship lock are also improved compared to the design scheme.The ship model verification shows that the ship can maintain a stable course when passing through the approach channel entrance and connection section,and the parameters such as rudder angle and drift distance all meet the standards,ensuring reliable navigation safety.