Optimal　models　of.　multi-stage　pre-stressed　Beam　String　Structure　(BSS)　are　given　in　this　paper,　which　seek　the　minimum　weight　or　deflection　with　optimal　cross-sectional　areas　of　the　members　and　optimal　value　of　pre-stressing　of　the　cable.　Then　the　process　of　analysis　is　presented　briefly.　The　method　put　forward　here　takes　advantage　of　ANSYS,　so　it　may　be　easy　to　learn　and　use　in　the　design　of　BSS.