Developing　a　rational　and　efficient　numerical　model　to　analyze　the　longitudinal　earthquake　response　of　shield　tunnel　has　become　a　hot　topic　in　the　field　of　underground　structure　seismic　research　in　recent　years.　Based　on　the　idea　of　scale　coupling,　this　study　proposed　a　multi-scale　numerical　model　that　can　capture　the　dynamic　response　of　ring　joint　in　the　vulnerable　part　of　shield　tunnel　precisely.　In　this　multi-scale　model,　the　non-focused　part　of　structure　is　described　by　the　Timoshenko　beam　&　nonlinear　spring,　while　the　focused　part　is　described　by　the　three-dimensional　＂refined　ring　joint＂.　The　multi-scale　model　is　subsequently　utilized　to　calculate　the　longitudinal　seismic　response　of　the　shield　tunnel　through　a　typical　site　with　a　soft-hard　stratum　junction.　In　addition,　the　influence　of　earthquake　wave　parameters　on　the　seismic　response　of　the　tunnel　structure　is　also　discussed　in　this　study.　Some　inspiring　conclusions　are　as　follows.　The　dynamic　response　of　the　shield　tunnel　rises　dramatically　near　the　soft-hard　stratum　interface　because　of　the　non-uniform　deformation　of　the　soil　in　that　area.　Strong　earthquake　waves　(with　high　PGA　or　PGV)　may　cause　nonlinear　increase　in　the　opening　deformation　of　a　ring　joint　and　the　yielding　of　several　joint　bolts.　Under　high　intensity　seismic　load,　the　service　state　of　joint　bolts　varies　widely,　and　the　damage　is　concentrated　in　one　region　of　the　ring　joint.