The　shear　failure　mode　and　failure　mechanism　of　12　CFRP-strengthened　concrete　beams　without　stirrups　were　analyzed.　The　stress-strain　curves　of　the　CFRP　beams　in　the　whole　process　were　obtained.　The　quantitative　effects　of　structural　size　and　CFRP　ratio　on　the　shear　strength　of　CFRP　are　discussed.　Furthermore,　a　formula　for　calculating　the　shear　strength　of　CFRP　is　proposed　and　compared　with　the　test　results,　the　test　results　of　others　and　the　standard　results　in　this　work.　It　is　found　that　the　structural　size　has　a　significant　influence　on　the　shear　strength　of　CFRP.　The　nominal　shear　strength　of　CFRP　decreases　significantly　when　the　structural　size　increases.　In　addition,　when　the　beam　depth　changes　from　300　mm　to　1　200　mm,　the　nominal　shear　strength　of　CFRP　decreases　by　about　50%,　which　has　an　obvious　size　effect.　Furthermore,　under　different　cross-section　sizes,　the　nominal　shear　strength　of　CFRP　increases　with　the　increase　of　CFRP　ratio　ρf,　but　with　the　increase　of　CFRP　ratio　ρf,　the　increase　amplitude　of　nominal　shear　strength　decreases,　showing　a　nonlinear　growth　trend.　Finally,　the　established　formula　for　calculating　the　shear　capacity　of　CFRP　could　predict　the　shear　capacity　of　CFRP　under　different　CFRP　ratio　and　section　size　scientifically.　©　2025　Chongqing　University.　All　rights　reserved.