The　use　of　modular-prefabricated　steel　structures　has　distinct　advantages,　such　as　rapid　construction,　industrial　production,　and　environmental　protection.　Although　this　type　of　structure　has　been　extensively　employed　around　the　world,　it　is　primarily　used　for　low-rise　buildings;　its　application　in　high-rise　buildings　is　limited.　This　paper　proposes　a　new　type　of　modular-prefabricated　high-rise　steel　frame　structure　with　diagonal　braces.　An　elastic-plastic　time-history　analysis　of　a　30-storey　building　during　rare　earthquakes　was　performed.　The　base　shear,　storey　drift,　stress,　damage　characteristics,　and　other　performances　of　the　structure　were　investigated.　According　to　the　mechanism　analysis,　finite　element　simulation,　and　model　test,　the　formulas　for　the　elastic　and　elastic-plastic　design　of　the　truss-column　connection,　column-column　flange　connection,　and　diagonal　brace-truss　connection　are　proposed　in　this　paper.　The　control　parameters　for　the　structural　design　are　also　discussed.　This　study　provides　an　important　reference　for　the　research　and　design　of　this　type　of　modular-prefabricated　high-rise　steel　structure.　The　design　method　has　been　compiled　into　a　design　specification　named　Technical　Specifications　for　Prefabricated　Steel　Frame　Structure　with　Diagonal　Bracing　Joints,　which　is　unique　for　this　type　of　structure.