The second-line ship lock expansion project of Wuxi Hub is taken as an example.The site selection and general layout concept of the second-line ship lock under compact site constraints with limited surrounding space are discussed.By adopting measures including corner,staggered layout,flood retaining line optimization and elimination of downstream berthing sections,the final recommended scheme is determined.Meanwhile,the navigation water flow conditions of the entrance area are further analyzed and optimized through physical model tests.Measures such as row piles + pile foundation plug structure,local dredging of the approach channel,rounding of corners,and the installation of diversion piers are adopted to improve the navigation water flow conditions of the approach channel.The maximum navigation flow of the ship lock is determined as 7,550 m3/s with a two-year return period.The innovation design for lock chamber,cofferdam,and baffle sill of the ship lock can provide references for similar projects.