Here,to　study　effects　of　corrosion　on　dynamic　mechanical　properties　of　reinforced　concrete　(　RC　)　beam,　a　two-stage　3D　meso　scale　numerical　model　of　corroded　RC　beam　was　established　considering　effects　of　corrosion　of　reinforcement,　strain　rate　and　heterogeneity　of　concrete　internal　structures.　The　non-uniform　corrosion　expansion　of　reinforcement　was　simulated　by　applying　non-uniform　radial　displacement,and　the　＂　final　state　＂　of　protective　layer　cracking　was　taken　as　the　＂　initial　input　condition＂　of　the　subsequent　dynamic　load　simulation　of　concrete　beam　to　obtain　its　dynamic　mechanical　behavior　after　corrosion.　After　verifying　the　rationality　of　the　numerical　model,　corrosion　cracking　behavior　of　protective　layer　caused　by　rebar　corrosion　and　variation　of　mechanical　properties　of　members　under　different　strain　rates　were　analyzed.　The　results　showed　that　rebar　corrosion　causes　obvious　longitudinal　cracks　in　concrete　beam,　and　load-bearing　capacity　of　concrete　beam　decreases　with　increase　in　corrosion　rate　of　steel　bars　;　under　high　strain　rates,　concrete　beam　has　punching-shear　failure,and　its　load-bearing　capacity　is　significantly　improved　;　load-bearing　capacity　loss　of　corroded　concrete　beam　is　approximately　linear　with　frequency　reduction　coefficient　(　reflecting　stiffness　loss)　of　corroded　beam,　and　load-bearing　capacity　under　low　strain　rates　is　more　sensitive　to　frequency　changes.　Finally,　based　on　regression　analysis　of　simulation　results,a　formula　to　predict　dynamic　flexural　capacity　of　RC　beam　considering　coupling　effects　of　corrosion　and　strain　rate　was　developed.　©　2023　Chinese　Vibration　Engineering　Society.　All　rights　reserved.