It　is　important　for　subway　approaching　excavation　and　safe　management　to　study　the　seismic　response　characteristics　of　closely-attached　intersecting　underground　subway　structures.　The　finite　difference　procedure　FLAC3D　is　used　to　simulate　the　seismic　response　of　typical　closely-attached　intersecting　underground　subway　structures　under　vertical　strong　ground　motion　in　Beijing,　of　which　the　seismic　response　characteristics　are　analyzed　carefully　and　compared　with　those　of　a　single　subway　station　as　well.　It　is　shown　that　there　are　significant　changes　in　the　vertical　displacement　and　the　stress　of　structures　between　the　single　subway　station　and　the　closely-attached　intersecting　subway　station　because　of　the　strong　interaction　of　the　upper　station　and　the　lower　tunnel,　which　is　also　in　connection　with　input　ground　motion,　and　that　the　monitoring　parts　have　the　same　variation　amplitudes.　As　soils　can　filter　high　frequency　component　of　ground　motion　significantly,　the　vertical　displacement　difference　and　the　vertical　stress　difference　between　the　above　two　kinds　of　subway　stations　under　vertical　strong　ground　motion　rich　in　high-frequency　waves　are　smaller　than　those　rich　in　low-frequency　waves,　while　they　are　not　sensitive　to　peak　acceleration　of　input　ground　motion.