The　stress　of　the　main　tower　of　a　cable-stayed　bridge　depends　on　the　connection　type　between　the　tower　and　deck.　In　order　to　study　the　most　suitable　longitudinal　damping　mode　for　a　long-span　cable-stayed　bridge.　In　this　article,　a　nonlinear　finite　element　model　is　established　based　on　a　large　span　concrete　cable-stayed　bridge　with　a　main　span　of　680　m.　Without　considering　the　influence　of　the　transverse　constraint,　the　damping　effect　of　the　elastic　connection　device　and　the　viscous　damper　is　simulated　when　the　longitudinal　seismic　load　is　input.　The　results　show　that　the　stiffness　of　the　main　beam　is　increased　by　installing　the　elastic　connection　device,　so　the　longitudinal　drift　frequency　of　the　main　beam　is　increased,　but　the　stiffness　of　the　structure　is　not　changed　by　installing　the　viscous　damper.　Both　viscous　dampers　and　elastic　connection　structures　can　reduce　the　longitudinal　displacement　of　the　beam　end,　but　viscous　dampers　are　more　favorable　for　the　stress　of　the　main　tower.　In　terms　of　damping　effect,　viscous　dampers　are　more　suitable　for　long-span　cable-stayed　bridges,　but,　in　terms　of　economy　and　parameter　control,　elastic　connection　devices　have　more　advantages.