Here,　taking　transfer　and　cleaning　room　structure　of　nuclear　power　plant　as　a　prototype,　finite　element　models　of　transfer-cleaning　room　structures　without　and　with　cantilever,　respectively　were　established.　Through　modal　analysis　and　dynamic　time　history　analysis　of　the　two　models,　effects　of　large　cantilever　on　aseismic　performance　of　transfer-cleaning　room　structure　were　analyzed,　and　its　dynamic　characteristics　and　aseismic　performance　were　explored.　The　results　showed　that　because　structural　stiffness　of　transfer-cleaning　room　structure　is　large　and　its　natural　vibration　period　is　short,　its　seismic　response　is　smaller　under　action　of　ground　motion　exceeding　the　design　basis,　and　the　overall　structure　is　still　in　elastic　working　state;　large　cantilever　significantly　reduces　stiffness　of　transfer-cleaning　room　structure,　prolongs　its　natural　vibration　period,　and　also　increases　the　overall　structure＇s　seismic　response,　but　this　increase　is　not　large;　transfer-cleaning　room　structure　with　cantilever　fully　satisfies　aseismic　performance　requirements.　©　2023　Chinese　Vibration　Engineering　Society.　All　rights　reserved.