From　the　mesoscopic　view,　combining　with　the　micro/mesoscopic　structural　character　of　concrete,　as　well　as　considering　the　nonlinear　binding-slip　behavior　between　a　steel　bar　and　concrete,　a　three　dimensional　meso-scale　numerical　model　and　the　method　for　a　reinforced　concrete　(RC)　cantilever　beam　were　set　up.　Based　on　the　numerical　method,　the　shear　performance　of　a　RC　cantilever　beam　under　cyclic　loading　was　analyzed,　the　numerical　results　are　well　fitted　with　the　experimental　results,　and　it　shows　the　feasibility　of　the　mesoscopic　numerical　method.　Then　on　this　basis,　the　shear-failure　process　of　different　stirrup-ratio-RC　cantilever　beams　is　further　simulated,　and　the　influence　regularity　of　stirrup　on　hysteretic　characteristic　and　the　shear　bearing　capacity　of　a　cantilever　beam　are　revealed.　The　research　shows　that:　1)　the　mesoscopic　numerical　model　can　better　simulate　the　mechanical　properties,　and　it　can　detailed　describe　the　development　process　of　cracks　in　concrete;　2)　with　the　increase　of　stirrup　ratio,　shear-bearing　capacity　and　ductility　increase,　but　with　the　increase　of　stirrup　ratio,　the　increasing　trend　of　RC-beam-shear-bearing　capacity　slow　down　gradually.　The　meso-scale　numerical　method　can　provide　a　theoretical　support　for　the　shear/bend　size　effect　of　beams　with/without　web　reinforcement.　©　2017,　Engineering　Mechanics　Press.　All　right　reserved.