After　coupling　long-period　seismic　motions　with　the　soil-structure　interaction　(SSI)　effect,　isolated　structures　can　easily　be　resonated,　and　the　seismic　response　of　the　structure　is　significantly　enhanced.　The　SSI　effect　can　alter　the　dynamic　characteristics　of　a　structure,　resulting　in　a　deviation　between　the　assumed　seismic-isolation　effect　of　the　rigid　foundation　and　the　theoretical　results.　To　investigate　the　dynamic　characteristics　and　seismic-response　laws　of　interlayer　structures　considering　SSI　under　long-term　seismic　motion,　four　types　of　ground　motions　(near-field　ordinary,　far-field　ordinary,　near-field　pulse,　and　far-field　harmonic　ground　motions)　were　selected,　and　two　structural　models　(rigid-foundation　and　soft　soil　foundation　interlayer　seismic-isolation　structure　models)　were　established.　Experiments　were　conducted　using　a　combination　of　shaking-table　tests　and　finite-element　simulations.　The　results　show　that　the　use　of　the　SSI　effect　caused　the　decrease　in　the　acceleration　response　of　the　upper　structure　of　both　models　under　four　types　of　seismic　motions　and　increased　the　seismic　peak　ground　acceleration　(PGA).　In　addition,　the　weakening　of　the　acceleration　response　of　the　upper　structure　under　ordinary　seismic　motion　is　significant　for　longer　periods　of　seismic　motion.　Furthermore,　when　considering　the　SSI　effect,　the　displacement　response　ratio　under　long　periods　and　ordinary　ground　motions　is　greater　than　that　of　rigid　foundations,　and　the　horizontal　deformation　of　the　isolation　layer　under　long-period　ground　motions　is　greater　than　that　under　ordinary　ground　motions.　This　shows　that　the　SSI　effect　weakens　the　interlayer　shear　force　under　ordinary　seismic　action　more　than　that　under　long-period　seismic　action.　When　PGA　increases,　the　interlayer　shear　force　response　of　the　interlayer　isolation　structure　model　with　a　soft　soil　foundation　under　a　long-period　seismic　action　may　be　smaller　than　that　of　the　rigid-foundation　model.