With　the　rapid　development　of　underground　space,　more　adverse　site　conditions　are　occurring　in　the　construction　of　underground　structures.　For　example,　a　subway　station　passes　through　longitudinally　inhomogeneous　geology.　When　the　subway　station　crosses　the　interface　of　soft　soil　and　hard　soil,　this　may　lead　to　the　destruction　of　underground　structures.　In　this　paper,　three-dimensional　(3D)　nonlinear　seismic　response　analysis　of　subway　stations　crossing　longitudinally　inhomogeneous　geology　subjected　to　obliquely　incident　P　waves　is　presented　based　on　actual　engineering　background.　The　earthquake　input　method　for　the　longitudinally　inhomogeneous　site　that　transforms　the　site　seismic　response　into　an　equivalent　nodal　load　is　first　developed　and　verified.　The　viscous-spring　artificial　boundary　is　used　to　simulate　the　radiation　damping　effect　of　infinite　domain　media.　Subsequently,　the　topographic　and　geological　effects　on　seismic　response　of　engineering　site　are　investigated.　Finally,　the　failure　mechanism　of　the　subway　station　structure　crossing　longitudinally　inhomogeneous　geology　under　the　obliquely　incident　P　waves　is　revealed.　The　investigation　demonstrates　that　the　plastic　zone　of　site　usually　appears　along　the　interface　between　the　hard　and　soft　soil　media,　and　appears　on　the　side　of　the　soft　soil.　The　sidewall　and　bottom　slab　of　the　structure　experience　obvious　tensile　damage　at　the　interface　location　between　the　hard　and　soft　soil　media.　The　results　show　that　topographic　and　geological　effects　should　be　considered　in　seismic　analysis　and　design　of　underground　structures　when　the　topography　and　geology　change　significantly.