This　paper　presents　a　comparative　study　on　the　size　effect　behaviors　of　shear　performances　of　concrete　shear　walls　reinforced　by　steel　bars　and　Basalt　Fiber　Reinforced　Polymer　(BFRP)　bars.　All　the　works　are　conducted　through　a　two-dimensional　meso-scale　numerical　simulation　model　representing　the　concrete　shear　wall.　The　horizontal　reinforcement　ratio　and　the　sectional　size　are　the　main　parameters　concerned　by　the　present　study.　Both　the　seismic　behaviors　under　cyclic　loading　and　the　size　effect　behaviors　of　the　shear　performances　were　simulated　and　investigated.　It　can　be　concluded　from　the　simulation　results,　(1)　the　use　of　steel　bars　or　BFRP　bars　as　horizontal　reinforcement　does　not　change　the　shear　failure　modes　of　concrete　shear　walls,　(2)　the　size　effect　on　the　nominal　shear　strength　of　BFRP　reinforced　concrete　(BFRP-RC)　shear　wall　is　more　significant　compared　to　that　for　steel-RC　shear　wall,　(3)　the　increase　of　horizontal　reinforcement　ratio　improves　the　shear　capacity　of　the　concrete　shear　wall,　while　weakens　the　size　effect　on　the　nominal　shear　strength,　and　(4)　the　size　effect　law　for　the　nominal　shear　strength　of　steel-RC　shear　wall　is　applicable　to　BFRP-RC　shear　wall.　Finally,　the　importance　of　considering　size　effect　in　the　evaluation　of　shear　performance　of　steel-/BFRP-RC　shear　wall　is　manifested　by　comparing　the　predictive　results　of　several　popular　design　codes　with　the　simulation　results.