The　narrower　on　lower　floors　and　the　wider　on　upper　floors　structure　is　used　in　the　National　Fitness　Center,　in　Ejin　Horo　Banner,　Inner　Mongolia,　which　has　the　characteristic　of　extreme　vertical　stiffness　irregularity.　The　elasto-plastic　performance　in　the　condition　of　static　stability　limit　state　becomes　the　key　factors　of　the　security　of　the　structure.　First,　the　performance　of　the　main　structure　in　the　condition　of　static　loading　was　analyzed　adopting　the　performance　target　put　forward　in　this　paper.　The　choice　of　the　multi-floor　structure　with　the　huge　grid　as　the　best　scheme　was　made　among　many　schemes.　Then　the　seismic　performance　studies　were　conducted　by　response　spectrum　analysis,　elastic　dynamic　time-history　analysis　and　elasto-plastic　dynamic　time-history　analysis　respectively.　The　key　part　of　the　analysis　is　the　irregularity　of　the　structure,　the　security　at　the　end　of　cantilever　and　the　elasto-plastic　performance　in　the　condition　of　major　earthquake.　Analysis　shows　that　the　structural　scheme　selected　based　on　the　performance　target　put　forward　in　this　paper　is　economic　and　reasonable,　and　the　static　and　seismic　performance　objectives　for　design　are　realized.