In　order　to　study　the　seismic　characteristics　of　cable-stayed　bridge　with　single　tower,　a　1:30　scaled　model　of　a　semi-floating　composite　cable-stayed　bridge　was　designed　and　tested　on　the　shaking　tables　under　multi-support　excitations　with　different　strong　earthquake　waves.　The　results　show　that　the　bearing　damage　and　failure　is　one　of　the　main　failure　modes　of　the　semi-floating　composite　cable-stayed　bridge　model　under　strong　earthquake　loading.　Compared　with　the　case　only　considering　unidirectional　horizontal　seismic　waves,　the　acceleration　responses　of　the　cable-stayed　bridge　model　with　the　semi-floating　system　are　more　affected　under　the　bidirectional　horizontal　earthquake　excitations,　but　the　effect　on　the　dynamic　displacement　response　is　less.　Under　the　bidirectional　horizontal　earthquake　excitations,　the　vertical　acceleration　at　the　middle-span　of　the　main　girder　cannot　be　ignored.　The　cable-stayed　bridge　model　with　the　semi-floating　system　is　more　severely　damaged　under　the　earthquake　waves　with　the　longer　predominant　period.　Meanwhile,　the　transient　forces　of　the　cables　are　far　greater　than　the　initial　cable　forces.　©,　2014,　Dongnan　Daxue　Xuebao　(Ziran　Kexue　Ban)/Journal　of　Southeast　University　(Natural　Science　Edition).　All　right　reserved.