Aimed　to　improve　safety　factor　against　cable　sliding　of　three-tower　self-anchored　suspension　bridge　(TSSB)　under　live　load,　the　sliding　saddle　system　was　presented　in　preiminary　design.　Considering　collision　between　saddle　and　baffleplate,　this　paper　compares　the　seismic　response　of　TSSB　with　sliding　saddle　to　TSSB　with　fixed　saddle　by　the　Finite　Element　Method.　The　analysis　result　shows　that　the　use　of　sliding　saddle　can　raise　safety　factor　against　cable　sliding　under　seismic　excitation,　but　along　with　increasing　of　seismic　response　of　main　towers,　and　mechanics　characteristics　of　saddle　becoming　more　complex.　Besides,　this　paper　discusses　the　influence　rule　of　impaction　stiffness　and　initial　gap　on　seismic　response.　Parametric　studies　shows　that　smaller　impaction　stiffness　of　sliding　saddle　can　reduce　the　seismic　response　of　saddle　and　the　critical　initial　gap　value　to　avoid　the　collision　of　sliding　saddle　is　suggested.