V-5Cr-5Ti　alloy　is　a　promising　candidate　structural　material　for　fusion-power　reactor　blankets.　However,　its　plastic　deformation　behavior,　which　is　important　to　the　safety　and　reliability　of　a　fusion　reactor,　is　not　sufficiently　understood.　The　present　paper　develops　a　physically　based　strain　hardening　model　to　characterize　the　plastic　deformation　of　V-5Cr-5Ti　alloy.　Using　miniaturized　specimens　of　V-5Cr-5Ti　alloy,　uniaxial　tensile　tests　and　microstructural　evolution　analysis　are　performed　at　different　strain　levels.　Microstructural　evolution　results　show　that　the　existence　of　Ti-enriched　second　phase　and　the　dislocation　interactions　are　critical　to　the　plastic　deformation　of　V-5Cr-5Ti　alloy.　On　the　above　physical　basis,　the　Ti-enriched　second　phase　and　the　evolution　equations　of　the　dislocation　density　are　developed,　while　the　flow　stress　rule　is　formulated　from　the　summation　of　athermal　stress,　thermally　activation　stress,　and　dispersed-phase　stress.　The　finite　element　method　based　on　the　user-material　subroutine　UMAT　(User-defined　Material　Mechanical　Behavior)　of　commercial　ABAQUS　code　(finite　element　analysis　software)　and　the　implicit　stress　update　algorithm　are　adopted　to　realize　the　proposed　physically　based　strain　hardening　model.　Results　suggest　that　this　new　strain　hardening　model　is　superior　to　conventional　models　for　providing　a　more　accurate　and　reasonable　prediction　of　the　plastic　deformation　behavior　of　V-5Cr-5Ti　alloy.　©　2020　Elsevier　B.V.