The　sectional　optimization　of　membrane　structure　with　discrete　variables　is　investigated　mapping　the　sectional　discrete　variables　to　continuous　variables.　A　two-stage　model　is　established　near　the　optimal　solution　of　sectional　optimization　of　continuous　variables,　and　the　quite　small　element　method　associated　with　the　dimensionless　variable　technique　is　adopted,　then　the　optimized　model　with　constraints　of　size　stress　and　displacement　under　multi-loadings　is　obtained.　The　secondary　exploitation　of　the　special　program　on　MSC.　Patran　and　MSC.　Nastran　is　carried　out,　the　numerical　examples　demonstrate　high　efficiency　of　the　method　and　feasibility　of　secondary　development.