In the optimal design of large prestressed aqueduct structure, the optimal design results need to be automatically drawn. In this paper, the parametric drawing method is proposed by combining high-level programming language FORTRAN and Auto LISP, and developed a designing system of mixed programming using FORTRAN and Auto LISP. The programming system is applied to the optimal design process of large prestressed aqueduct with rectangle and U-shaped cross-section. The optimal design result is automatically transformed into visual graphics (documents), therefore realized the automatic drawing. In this way, designers’ graphics labor intensity and repeated, complicated calculation can be reduced and the design cycle can shorten. Data files (*.DAT) and graphics files (*.LISP) can be generated not only by FORTRAN, but also by other high-level programming languages such as C++, VC etc.