In　order　to　investigate　the　dynamic　shear　failure　mechanism　and　size　effect　law　of　deep　concrete　beams　with　Basalt　Fiber　Reinforced　Polymer　(BFRP)　bars,　a　three-dimensional　meso-scale　numerical　model　of　BFRP　reinforced　concrete　deep　beams　was　established　considering　concrete　heterogeneity,　concrete　/BFRP　reinforcement　interaction,　and　strain　rate　effect　of　concrete　and　BFRP　bars　in　material　level.　Firstly,　the　rationality　and　accuracy　of　the　numerical　simulation　method　are　verified　by　the　existing　experimental　data.　Then,　the　shear　failure　modes　and　failure　mechanisms　of　the　geometrical-similar　BFRP-reinforced　concrete　deep　beams　with　different　sizes　under　different　strain　rates　were　studied　by　the　numerical　simulation　method.　The　influence　of　beam　depth,　stirrup　ratio　and　strain　rate　on　the　shear　failure　of　BFRP-reinforced　concrete　deep　beams　and　the　corresponding　size　effect　law　were　analyzed.　The　results　indicate　that:　The　failure　modes　of　beams　under　dynamic　loading　are　different　from　those　under　static　loading,　but　they　all　show　size　effect;　Both　the　strain　rate　and　the　stirrup　rate　can　effectively　improve　the　bearing　capacity　of　the　beam　and　weaken　the　shear　size　effect,　but　the　effect　of　strain　rate　is　significantly　greater　than　that　of　stirrup　rate.　©　2023　Nanjing　University　of　Aeronautics　an　Astronautics.　All　rights　reserved.