Seismic　performance　of　RC　beam-column　joints　under　low　cyclic　loading　with　different　cycle　numbers　was　analyzed　by　FEA　software,　to　study　duration　effect　of　long　period　ground　motion.　The　loading　with　different　cycle　numbers　was　used　to　simulate　the　duration　of　the　ground　motion.　Hysteretic　curves　and　skeleton　curves　of　the　joints　were　obtained.　The　results　indicate　that　as　the　cycle　number　increases,　the　capacity　and　ductility　of　the　joint　declines,　and　the　stiffness　of　the　joint　attenuates　faster.