The optimal design of an overall sluice structure on a soft foundation was studied,with a sluice in North Jiangsu Province as a case study. A mathematical model for the optimal design of the sluice was established, in which the key geometrical parameters for the sluice chamber and pile group foundation structure were the design variables, the minimum cost for the construction of the sluice chamber and pile group foundation was the objective function, and the antisliding stability of the chamber structure, bearing capacity of the foundation, stress in the basement, strengths of the chamber and pile foundation structures, settlement of the chamber structure, and horizontal displacement at the top of piles were the main constraint conditions. Using the optimization module in the software ANSYS, the optimal design schemes for the overall sluice structure and chamber structure were obtained, respectively. Compared with the optimal design scheme for the chamber structure, the optimal design scheme for the overall sluice structure shows that the total cost in the sluice construction decreases by 2.7％, and the horizontal displacement at the top of piles reaches the critical limit, demonstrating a better optimization effect.