A　new　modular　prefabricated　steel　structure　that　is　characterized　by　high　construction　efficiency,　low　labor　intensity,　convenient　quality　control,　and　consumption　of　excess　capacity　of　the　steel　industry　is　used　in　this　paper.　The　structural　design　and　in-depth　research　are　performed　in　this　paper　using　a　finite-element　method.　The　strength,　rigidity,　and　stability　of　the　structure　and　relevant　components　are　calculated.　The　results　show　that　all　indices　are　compliant　with　the　standards　and　regulations.　Through　pushover　analysis　and　finite-element　analysis　of　the　joints,　the　mechanical　characteristics　of　the　system　under　the　design　load　and　the　failure　mode　under　the　ultimate　load　are　obtained,　together　with　the　elastoplastic　development　pattern;　yield　failure　mode　and　potential　mechanisms　were　further　explored.　The　results　also　show　that　the　structural　system　is　consistent　with　the　design　philosophy　of　＂strong　joint,　weak　component＂.　The　system　is　basically　in　the　elastic　stage　with　reasonable　yield　mechanisms　in　case　of　major　earthquakes.　Therefore,　both　the　elastic　and　elastoplastic　performances　comply　with　structural　design　requirements.　This　paper　presents　an　innovative　design　method　that　suits　the　system　and　provides　a　technical　reference　for　the　design　of　similar　structures.