Considering　soil-structure　interaction　(SSI)　effect　on　soft　soil　foundation　will　affect　the　seismic　isolation　effect　and　dynamic　characteristics　of　the　isolated　structures.　The　seismic　response　of　long-period　structures　such　as　isolated　buildings　under　the　far-field　long-period　ground　motion　is　strong,　which　may　be　greater　after　considering　the　SSI　effect.　In　order　to　explore　the　mechanism　of　dynamic　response　and　seismic　isolation　performance　of　the　system　of　pile,　soil　and　inter-story　isolated　structure　under　the　far-field　long-period　ground　motion,　the　shaking　table　test　was　carreid　out　on　the　model　of　the　inter-story　isolated　structure　on　the　soft　soil　foundation.　The　story　acceleration　and　displacement　response　of　the　isolation　layer　and　the　isolated　structure　under　the　far-field　long-period　ground　motion　and　ordinary　ground　motion　were　compared　and　analyzed.　The　results　show　that　the　soft　soil　foundation　has　an　obvious　filtering　effect,　which　can　mitigate　the　high-frequency　component　and　enlarge　the　medium　and　low-frequency　components.　The　seismic　isolation　effect　of　the　inter-story　isolated　structure　under　the　ordinary　ground　motion　is　more　significant,　and　the　seismic　isolation　effect　decreases　with　the　increase　of　the　peak　ground　acceleration,　while　the　seismic　isolation　effect　under　the　far-field　long-period　ground　motion　is　far　worse　than　that　under　the　ordinary　ground　motion.　The　foundation　and　the　isolation　layer　have　an　obvious　rotation　effect,　and　the　isolation　layer　has　a　certain　amplification　effect　on　the　rotation　of　the　foundation.　The　amplification　effect　is　more　obvious　under　the　far-field　long-period　ground　motion　than　that　under　the　ordinary　ground　motion,　which　is　related　to　the　larger　response　of　far-field　long-period　ground　motion　to　the　displacement　of　the　isolation　layer.　©　2021,　Editorial　Office　of　Journal　of　Building　Structures.　All　right　reserved.