The　seismic　damage　state　of　building　structure　can　be　rapidly　evaluated　by　coupling　effect　of　structural　displacement　response　and　periodic　characteristics.　Firstly,　the　fundamental　period　calculation　formula　that　adapts　to　the　deformation　pattern　and　distribution　mode　of　horizontal　seismic　action　for　reinforced　concrete　frame　structure　is　derived.　Secondly,　the　seismic　damage　assessment　standard　of　building　structure　considering　period　variation　is　established.　Then,　the　seismic　damage　assessment　method　of　building　structure　is　constructed.　Finally,　the　seismic　damage　example　is　used　to　verify　the　established　evaluation　method.　The　results　show　that　the　established　research　method　has　high　accuracy　and　good　engineering　practicability.