With　the　intensive　development　of　metropolitan　downtown　areas,　underground　and　above-ground　space　will　be　developed　simultaneously.　Taiyuan　Metro　Line　3　and　Viaduct　that　is　above-ground　will　be　jointly　built.　This　paper　takes　the　co-construction　of　Tower　Street　metro　station　and　Viaduct　as　the　research　object,　a　two　dimensional　finite　difference　element　model　is　established　by　FLAC2D　of　soil—underground　station-　above-ground　bridge.　Site　conditions　of　liquefaction　and　non-liquefaction　when　we　use　plain　concrete　and　graded　gravel　soils　as　the　materials　of　the　conversion　layer　respectively　are　considered　here,　and　the　seismic　response　of　subway　station　structure　and　conversion　layers　are　analyzed.　The　results　show　that　the　horizontal　deformation　of　station　under　liquefaction　condition　is　larger　when　uses　plain　concrete　as　the　material　of　conversion　layer　than　to　use　graded　gravel　soils.　The　position　where　the　maximum　value　of　the　vertical　stress　or　horizontal　stress　of　cushion　occurs　is　nearly　the　same,　location　where　the　maximum　value　of　the　internal　force　of　the　underground　structure　occurs　is　also　the　same　no　matter　it’s　on　the　site　of　liquefaction　or　non-liquefaction.　With　the　increase　of　the　input　peak　value　of　ground　motion,　the　stress　of　the　conversion　layer　and　the　internal　force　of　the　underground　structure　on　the　liquefied　site　increase　obviously　which　are　much　larger　than　that　on　the　non-liquefied　site.　This　study　not　only　provides　the　basis　for　evaluating　the　feasibility　of　the　project,　but　also　offers　reference　for　the　construction　of　similar　projects　in　the　future.　©　2017　15th　International　Conference　of　the　International　Association　for　Computer　Methods　and　Advances　in　Geomechanics