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.