The second-line ship lock project of Xijin Water Conservancy Project plays an important role in the development of the Xijiang River shipping and watershed economy.In order to study the interaction between the second-line ship lock layout and the layout of the original ship lock,hydraulic model test was carried out to study the water flow conditions under two different layout schemes,by comparing the three indices of longitudinal,transverse and backflow velocities of the first and second line ship lock gates.The comparative analysis shows that when using the common layout scheme of the first and second shiplock gateways,in the case of flood flow,the horizontal and return flow velocity in the area can’ t meet the standard requirements.When using the next navigation channel door to separate the type of layout,flow velocities of the second-line lock under the entrance area of the lower approach channel at all levels of navigation traffic basically meet the code requirements.