Abstract: In this paper a new structure type of face rockfill dam is discussed. Take it to be research object, the new method of designing the section of rockfill dam is investigated.The mathematical model for section optimal design is set up. By using the complex method of nonlinear programming, the optimal section is calculated. As an example,the method is used to determine the section of Gongboxia dam. The results demonstrate that method proposed in this paper is reasonable.