Yujiang river is an important part of the Xijiang river golden waterway in Guangxi, and the shiplock of Laokou shipping hub is very important. The designed water head of the lock is 14.5 m, and the filling time is required to be not more than 10 min. According to emptying water system design specifications and the characteristics of this project, we choose a more compact structural arrangement as the water filling & emptying system for the lock wall’s holes. Based on the data of similar locks home and abroad, and through calculation and optimization of hydraulic model test, we determine the overall layout and key dimensions of all parts. Model test results show that the hydraulic characteristics of water filling & emptying system meet the requirement of the code, and has achieved the desired objectives.