The　structural　seismic　vulnerability　analysis　is　crucial　to　evaluate　the　loss　of　earthquake　disaster.　Based　on　the　incremental　dynamic　analysis　(IDA)　method　and　the　theory　of　performance-based　design,　the　structural　seismic　capacity　probability　function　can　be　derived　from　the　definitions　and　specified　values　for　damage　states　in　seismic　codes,　and　seismic　demand　probability　function　can　also　be　obtained　by　IDA.　The　vulnerability　analysis　method　is　put　forward　based　on　design　performance,　by　which　the　seismic　response　of　integral　structure　can　be　assessed　effectively.　The　seismic　vulnerability　analysis　of　a　steel　frame　structure　is　carried　out　with　floor　slab　effect　considered　or　not.　Failure　state　assessment　and　seismic　risk　analysis　are　performed　from　the　perspective　of　probability　of　damage.　Finally　conclusions　are　drawn　that　the　existing　of　floor　slab　will　lead　to　the　reduction　in　structural　ductility,　seismic　capacity,　and　the　capability　to　resist　structural　collapse.　The　results　provide　bench　mark　reference　for　seismic　design,　reinforcement　and　damage　evaluation　after　earthquake　disaster.　©　2016,　Engineering　Mechanics　Press.　All　right　reserved.