Based　on　the　foundation　dynamic　impedance　calculation　formulas　suggested　by　different　scholars,　the　S-R　(swing-rocking)　model　was　modified　by　combining　with　the　integral　finite　element　method　and　starting　from　the　view　point　of　engineering　application.　The　practical　simplified　calculation　method　suitable　for　the　soil-structure　dynamic　interaction　analysis　of　long-span　spatial　structures　was　proposed.　Then,　the　model　of　soil-grid　structure　interaction　was　established　according　to　the　modified　S-R　model,　and　the　three-dimensional　finite　element　model　verified　was　also　established　for　a　comparative　analysis.　The　study　showed　that　the　natural　vibration　properties　and　seismic　response　of　the　soil-grid　structure　interaction　model　based　on　the　modified　S-R　model　reveal　same　regularities　and　agree　well　with　those　of　the　3-D　FE　model,　the　rationality　of　the　modified　S-R　model　is　verified;　the　nodal　maximum　displacement　error　and　peak　acceleration　error　of　the　soil-grid　structure　interaction　system　established　with　the　foundation　dynamic　impedance　calculation　formulas　proposed　by　Gazetas　are　less　than　8.0%,　and　the　maximum　stress　error　of　members　is　less　than　10%　compared　with　those　obtained　with　the　3-D　FE　model　under　different　seismic　waves;　thus　the　foundation　dynamic　impedance　calculation　formulas　proposed　by　Gazetas　are　more　suitable　for　the　analysis　of　soil-large　span　spatial　structure　interaction　and　have　a　higher　precision.　©,　2015,　Chinese　Vibration　Engineering　Society.　All　right　reserved.