Abstract: This paper addresses the local stability problem of truss members under compression. Based on the full stress design method, a function relationship between the sectional area and the inertia moment is established using similar transformation. With the critical stress, iterative formulas of sectional area are derived for members with large, middle and small flexibility, respectively. The sectional optimization of truss is achieved, satisfying size, stress and local stability constraints. A more rational and exact truss optimization software package with local stability constraints is developed in MSC/NASTRAN using Patran Commend Language.