Natural　vibration　tests　of　single-cable-stayed　beam　and　double-cables-stayed　beam　are　conducted.　Models　of　the　two　structures　are　established　by　the　finite　element　method　for　the　global　dynamic　analysis　of　cable-stayed　bridges,　and　their　accuracy　is　verified　by　the　test　results.　According　to　the　finite　element　analysis　of　single-cable-stayed　beams　to　four-cables-stayed　beams,　the　influence　of　the　existence　and　number　of　cables　on　in-plane　natural　frequency　is　large,　but　that　on　out-of-plane　natural　frequency　is　small.　Because　cables　support　the　beam　vertically,　the　increase　in　the　number　of　cables　will　lead　to　an　increase　in　the　in-plane　natural　frequency　of　cable-stayed　beam　structures.　By　assuming　the　cable＇s　vertical　support　to　be　elastic　and　considering　the　effect　of　the　horizontal　component　of　cable　force　on　the　axial　force　of　the　beam,　the　frequency　equation　and　mode　function　of　in-plane　natural　vibration　for　multi-cables-stayed　beams　are　derived.　The　validity　and　applicability　of　the　simplified　formulas　are　verified　by　finite　element　analyses.　©　2017,　Engineering　Mechanics　Press.　All　right　reserved.