In　order　to　analyze　the　effects　of　CFRP　ratio　on　the　failure　mode　and　shear　capacity　of　large-size　(beam　height　over　600　mm)　beams　strengthened　by　CFRP,　as　well　as　the　effect　of　CFRP　in　large-size　beams　wrapped　by　CFRP,　experimental　investigation　of　four　large　size　(beam　height　1　200　mm)　U-shaped　CFRP　wrapped　non-abdominal　reinforced　concrete　beams　(concrete　strength　49　MPa)　with　shear　span　ratio　of　1.5　and　CFRP　ratio　of　0　~　0.50　5%　was　designed.　The　results　show　that　the　shear　capacity　of　beams　strengthened　with　different　CFRP　ratios　increases　by　57%,　72%　and　77%,　respectively.　However,　with　the　increase　of　the　CFRP　ratio,　the　shear　strengthening　efficiency　of　CFRP　decreases　by　57%,　10%,　and　3%,　respectively.　It　indicates　that　the　enhancement　of　the　shear　capacity　of　strengthened　beams　does　not　linearly　increase　with　the　increase　of　the　amount　of　CFRP.　In　addition,　it　is　found　that　the　shear　contribution　of　CFRP　increases　with　the　increase　of　CFRP　ratio,　but　the　strengthening　efficiency　shows　a　decreasing　trend.　The　accuracy　and　safety　of　the　calculation　formula　of　shear　capacity　of　relevant　design　specifications　were　discussed　based　on　the　test　results.　The　European　specification　(fib-TG　9.3　2001)　is　the　most　conservative,　and　the　Chinese　specification　(GB　50367—2013)　is　the　closest　to　the　test　value.　©　2023　Science　Press.　All　rights　reserved.