The　concrete　structures　under　impact　loading　duress　may　be　destroyed　within　an　extremely　short　period　of　time.　The　importance　and　complexity　of　exploration　on　the　impact　resistance　of　concrete　members　make　this　area　still　open　for　discussion.　In　the　present　study,　a　3-D　mesoscale　numerical　model　was　established　to　investigate　the　effect　of　the　combination　of　impact　mass　and　velocity　on　the　mechanical　behavior　of　reinforced　concrete　(RC)　beams　subjected　to　impact　loadings.　Heterogeneity　of　concrete　and　strain　rate　effects　of　concrete　and　steel　bars　were　taken　into　account.　Furthermore,　nonlinear　interaction　between　the　concrete　and　steel　bars　was　considered　herein.　Results　from　macroscale　and　mesoscale　simulation　were　compared　with　the　available　physical　tests,　indicating　that　the　mesoscale　numerical　model　can　better　represent　the　influence　of　heterogeneity　of　concrete　on　the　mechanical　behavior　of　RC　beams.　Five　different　impact　energy　levels　were　involved　to　study　the　effect　of　the　combination　of　impact　mass　and　velocity　on　the　impact　resistance　of　RC　beams.　At　last,　the　residual　bearing　capacity　and　natural　frequency　of　impacted　RC　beams　were　numerically　calculated　and　their　relationship　was　discussed.　It　is　indicated　that　the　deformation　of　RC　beams　is　influenced　strongly　by　the　impulse,　which　increases　with　the　increasing　impact　mass　at　identical　impact　energy.　Besides,　the　failure　mode　of　RC　beams　turns　from　shear-dominant　failure　mode　to　bending　shear　failure　mode　with　the　increase　of　impact　mass,　accompanied　by　the　increase　of　energy　dissipation　of　steel　bars　and　the　whole　member.　Despite　this,　in　the　present　work,　the　combination　of　the　impact　mass　and　velocity　had　little　influence　on　the　damage　extent　(based　on　the　performance)　of　the　RC　beams.　Moreover,　an　empirical　relationship　between　the　residual　bearing　capacity　and　the　natural　frequency　of　the　impacted　RC　beams　was　established　as　a　rough　reference　for　damage　evaluation　in　engineering　practice.