Focusing on the issue of reasonably determining the axial distance between two ship locks in a reconstruction and expansion project，this paper analyzes the relevant clauses in the current code and the research status. Then，the paper puts forward an analysis process of determining lock sites，deciding the initially proposed spacing，adjusting the spacing，and analyzing and reviewing the spacing to determine the axial distance between two ship locks. For this purpose，it adopts the method of combining theory with practice，takes into account factors influencing the axial distance between two ship locks，and combines engineering experience with the research results of existing projects. Furthermore，it proposes the corresponding calculation formula. Finally，the paper selects three representative ship lock projects and applies the above analysis process and corresponding calculation formula to them. The results show that the proposed technical route and calculation formula are reasonable and feasible.