Aiming　at　the　design　of　the　high-rise　prefabricated　steel　frame　with　inclined　braces,　which　was　applied　in　the　S30　project　of　Broad　Group,　the　methods　of　mode-superposition　response　spectrum　and　time　history　analysis　were　used　for　the　finite　element　numerical　simulation　of　the　whole　structure,　and　the　stress　and　displacement　responses　under　frequent　earthquakes　were　obtained.　The　elastic　design　of　the　whole　structure　was　performed　and　the　design　methods　are　summarized　in　the　paper.　The　bearing　capacity　of　column-column　seat　flange　plate　connection　was　designed　according　to　specifications,　and　the　strength　and　stiffness　of　the　connection　were　analyzed　and　tested　by　finite　element　analysis　and　model　test.　The　model　test　of　beam-column　joint　was　performed,　and　the　stiffness　changing　law　was　obtained.　The　method　of　building　simplified　analysis　model　of　beam-column　joint　by　spring　element　for　whole　structure　analysis　was　proposed.　The　structural　design,　numerical　simulation　and　model　test　results　show　that　the　influence　of　steel　stair　to　stiffness　of　the　whole　structure　could　be　ignored,　there　is　no　need　to　build　stair　model　in　the　whole　structure.　The　seismic　performance　of　this　new-type　structure　system　satisfies　the　requirements　of　current　specifications,　and　its　lateral　deformation　curve　locates　between　those　of　frame　and　shear　wall　structures.　The　inclined　braces　decrease　the　stress　within　the　connection　region,　increase　the　stiffness　of　the　structure,　and　play　a　role　of　reducing　the　calculation　length　of　column　and　protecting　the　column-column　seat　connection　and　beam-column　connection.　The　column-column　seat　flange　plate　meets　strength　requirement　and　behaves　as　rigid　connection,　the　continuity　of　strength　and　stiffness　of　column　is　guaranteed.　©,　2015,　Science　Press.　All　right　reserved.