The ship lock’s expansion and renovation in a narrow space is influenced by many factors,and the rationality of the general layout of lock position is particularly important.Taking an expansion and renovation engineering of ship lock for example,considering comprehensively the site selection,the width of shared approach channel,the effect on the second-line ship lock’s main structure and partition dikes in the process of construction,the layout of construction cofferdam,as well as the requirement of flood control,we carry out a research on the comparison and selection of the scheme.The lock layout scheme determined at last is that the distance between two locks’ axial lines is 80 m and the distance along river flow direction between the lower lock head of expansion and renovation the first-line ship lock and the lower lock head of the second-line ship lock is 4.4 m. Moreover,suggestions are presented for the follow-up engineering design.