For　subway　stations　in　a　site　with　thin　soil　layers　on　the　engineering　rock,　the　lower　part　of　the　subway　station　is　embedded　in　the　hard　rock　mass　and　the　upper　part　is　buried　in　the　soil　layers.　The　presence　of　the　soil-rock　interface　may　lead　to　significant　increase　to　the　seismic　responses　of　the　adjacent　soil　masses　and　underground　structures.　In　this　paper,　the　effect　of　the　soil-rock　interface　position　on　the　seismic　response　of　a　twostory　and　three-span　subway　station　structure　is　investigated　by　numerical　analyses.　It　is　found　from　the　numerical　analyses　that　a　most　detrimental　soil-rock　interface　position　exists　and　makes　the　underground　structure　have　maximum　responses　under　a　given　artificial　earthquake　motion.　For　the　upper　floor,　the　most　detrimental　soil-rock　interface　position　is　near　the　middle　slab.　For　the　lower　floor,　the　most　unfavorable　soil-rock　interface　position　is　near　the　bottom　slab.　Softer　site　generally　leads　to　greater　structural　responses　under　the　same　intensity　of　ground　motion　excitation.　On　the　basis　of　the　above　findings,　three　earthquake　motions　included　above　an　artificial　earthquake　motion　and　other　two　real　earthquake　motions　and　three　burial　depths　of　structure　are　further　studied.　Same　conclusions　can　be　obtained　for　the　structure　with　different　burial　depths　or　subjected　to　different　input　earthquake　motions.　The　conclusions　drawn　from　the　numerical　examples　of　this　paper　may　be　useful　for　seismic　design　of　subway　station　structure　buried　in　shallow　soil　layers　on　rock.