With　increase　in　structures＇　sizes,　correctly　predicting　the　varying　trend　of　aseismic　performance　and　anti-bending　strength　of　reinforced　concrete　(RC)　cantilever　beams　under　seismic　loads　is　of　great　importance　to　assess　the　safety　of　RC　frames.　Here,　five　groups　of　RC　cantilever　beams　with　geometric　similarity　and　a　shear　span　ratio　of　4　were　designed　and　tested　under　low　cyclic　loading.　The　relationships　between　beams＇　sizes　and　their　mechanical　behaviors　including　failure　pattern,　ductility,　energy-dissipating　capacity,　stiffness　degradation　and　bending-bearing　capacity　were　explored.　The　results　indicated　that　(1)　the　failure　patterns　of　all　the　tested　RC　beams　with　different　structural　sizes　are　similar,　all　the　beams　damage　at　the　fixed　end　due　to　cumulative　compressions;　(2)　with　increase　in　beams＇　sizes,　their　ductility　increases,　but　their　energy-dissipating　capacity　and　stiffness　degradation　do　not　change;　(3)　there　are　obvious　size　effects　for　the　nominal　anti-bending　strength　of　these　RC　beams　under　low　cyclic　loading;　(4)　the　size　effects　of　RC　cantilever　beams　under　cyclic　loading　can　be　described　well　using　Baant　size　effect　theory.　©　2017,　Editorial　Office　of　Journal　of　Vibration　and　Shock.　All　right　reserved.