The water system of an inner lake in a planned residential district is connected to the Tuanbo reservoir. To pass through the city road between this residential district and the Tuanbo reservoir and effectively control the water table level of the inner lake, two sluices with two box-culverts will be built under the city road. In the existing design, the cross-section and the base slab of the sluices are relatively greater than what is necessary, which is on the conservative safer side but not as economical. Considering the project requirements and load characteristics, this paper proposes different design solutions for the cross section of the sluices through comparison and analysis of the stresses and foundation deformations on the sluice walls, and base slab by means of FEM and computer simulation. As a result, an optimal cross-sectional structure of the sluices was selected, which significantly reduces the use of concrete, and is much more cost efficient than the existing design.