According　to　the　traveling　wave　effect　on　the　seismic　response　of　large　span　structure,　this　paper　took　a　main　span　of　260　meters　of　half-through　steel　arch　bridge　as　an　example　and　used　large　mass　method　to　realize　multi-support　excitation　of　traveling　wave　effect.　Through　selecting　five　sections,　study　on　the　traveling　wave　effect　of　seismic　response　of　bridge　were　made　under　diverse　phase　difference,　and　the　comparative　analysis　with　result　of　uniform　excitation　were　carried　out.　The　calculation　showed　that　the　former　seismic　response　was　greater　than　the　latter＇s　and　the　peak　of　vertical　displacement,　axial　force　and　transverse　moment　was　respectively　10.9,　6.5　and　5.1　times　of　the　latter＇s　when　the　phase　difference　was　5.2　s.　With　decrease　of　the　phase　difference,　the　displacement　and　internal　force　of　the　structure　present　decreasing　trend　when　considering　the　traveling　wave　effect.　Therefore,　the　traveling　wave　effect　should　be　considered　in　the　aseismic　design　of　long-span　Bridges.