The　dynamic　behavior　of　the　Sanxianzhou　Cable-Stayed　Bridge　in　Fuzhou,　Fujian　Province,　P.　R.　China　with　a　single　tower,　with　a　main　span　of　238　m,　has　been　investigated　by　full-scale　ambient　vibration　testing.　The　output-only　data　modal　parameter　identification　were　carried　out　by　using　the　peak　picking　(PP)　of　average　normalized　power　spectral　densities　(ANPSDs)　in　frequency-domain　and　stochastic　subspace　identification　(SSI)　in　time-domain.　For　this　bridge,　total　17　vibration　modes　were　identified　in　the　frequency　range　of　0-5Hz,　and　agreed　well　with　that　from　finite　element　model.　These　identified　modal　parameters　will　serve　as　a　basis　in　the　finite　element　model　updating,　structural　damage　detection　condition　assessment,　and　long-term　health　monitoring　on　service.