The　direct　finite　element　method　is　a　type　commonly　used　for　nonlinear　seismic　soil-structure　interaction　(SSI)　analysis.　This　method　introduces　a　truncated　boundary　referred　to　as　an　artificial　boundary　meant　to　divide　the　soil-structure　system　into　finite　and　infinite　domains.　An　artificial　boundary　condition　is　used　on　a　truncated　boundary　to　achieve　seismic　input　and　simulate　the　wave　radiation　effect　of　infinite　domain.　When　the　soil　layer　is　particularly　thick,　especially　for　a　three-dimensional　problem,　the　computational　efficiency　of　seismic　SSI　analysis　is　very　low　due　to　the　large　size　of　the　finite　element　model,　which　contains　an　whole　thick　soil　layer.　In　this　paper,　an　accurate　and　efficient　scheme　is　developed　to　solve　the　nonlinear　seismic　SSI　problem　regarding　thick　soil　layers.　The　process　consists　of　nonlinear　site　response　and　SSI　analysis.　The　nonlinear　site　response　analysis　is　still　performed　for　the　whole　thick　soil　layer.　The　artificial　boundary　at　the　bottom　of　the　SSI　analysis　model　is　subsequently　relocated　upward　from　the　bottom　of　the　soil　layer　(bedrock　surface)　to　the　location　nearest　to　the　structure　as　possible.　Finally,　three　types　of　typical　sites　and　underground　structures　are　adopted　with　seismic　SSI　analysis　to　evaluate　the　accuracy　and　efficiency　of　the　proposed　efficient　analysis　scheme.