Modularized　prefabricated　steel　structures　have　become　the　preferred　design　in　the　industrialization　of　steel　structures　due　to　their　advantages　of　fast　construction　speed,　high　degree　of　industrialization,　low　labour　intensity,　and　more.　Prefabricated　steel　structures　have　some　engineering　applications,　but　all　are　low-rise　structures　with　few　applications　in　the　field　of　high-rise　buildings.　Using　finite　element　analysis　with　line　and　solid　elements,　full-scale　experiments　were　conducted　to　study　the　single-span　frame,　which　is　the　core　load-bearing　part　of　a　modularized　prefabricated　high-rise　steel　frame　structure　with　inclined　braces.　The　mechanical　mechanisms,　computation　methods,　and　design　formulas　of　truss　girders　were　obtained　by　comparing　the　finite　element　and　model　experiments　and　building　a　theoretical　and　experimental　basis　for　the　compilation　of　design　codes.　The　mechanical　characteristics　under　design　load,　the　deformation　and　stress　state,　the　elastic-plastic　law　of　development,　and　the　yield　failure　mode　and　mechanism　under　horizontal　ultimate　load　were　also　obtained.　Based　on　theoretical　analysis,　finite　element　analysis,　and　experiments,　the　design　method　of　this　frame　was　summarized　and　incorporated　into　the　design　code.