A　three-dimensional　meso-scale　numerical　model,　which　considers　(1)　the　concrete　meso-structures,　(2)　the　bond　slip　between　concrete　internal　structures　and　steel　bars,　and　(3)　the　stripping　behavior　of　carbon　fiber　reinforced　polymer　(CFRP)　cloth　from　the　surface　of　the　concrete　component,　is　established　to　investigate　the　effects　of　concrete　strength　and　the　CFRP　cloth　ratio　on　the　shear　performance　of　reinforced　concrete　(RC)　beams.　On　the　basis　of　verifying　the　rationality　of　the　shear　failure　model　and　the　feasibility　of　the　CFRP　reinforcement　simulation　method,　30　orthogonally　designed　numerical　models　of　six　kinds　of　concrete　strength　and　five　kinds　of　CFRP　cloth　ratios　were　designed　and　established.　Based　on　the　numerical　simulation　results,　this　paper　analyzes　the　damage　evolution　of　the　CFRP–concrete　interface,　the　variation　trend　of　CFRP　strain　along　the　height　direction　of　beam,　the　failure　mode,　and　the　load-displacement　curve.　Results　show　the　following:　(1)　With　the　increase　of　concrete　strength　grade　and　CFRP　cloth　ratio,　the　shear　strength　of　RC　beams　strengthened　with　increases　in　CFRP　cloth　ratio,　the　influence　range　of　concrete　strength　grade　is　24–50%,　and　the　influence　range　of　the　CFRP　cloth　ratio　is　10–25%;　(2)　The　improvement　range　decreases,　and　the　improvement　range　of　the　concrete　strength　grade　decreases,　and　the　reduction　range　is　about　20%;　(3)　Based　on　the　simulation　results,　influences　of　concrete　strength　and　CFRP　cloth　ratio　on　the　shear　strength　of　CFRP　cloth-strengthened　RC　beams　are　quantitatively　considered.　©　2023　by　the　authors.