Interfacial　microstructure　characteristics　(e.g.,　volume　fraction,　thickness,　moduli)　are　crucial　to　the　overall　mechanical　properties　of　graphene/metal　nanocomposites.　Herein,　we　investigate　the　effects　of　different　interfacial　characteristics　on　simultaneous　improvement　of　strength　and　plasticity　of　nanocomposites.　Graphene　nanoplatelets　(GNPs)　reinforced　Ti6Al4V　composites　with　appropriate　interfacial　effects　are　first　fabricated　based　on　powder　metallurgy.　Combining　the　interphase　model,　the　field　fluctuation　method,　the　second-order　stress　moment　and　continuous　damage　theory,　the　multiscale　theoretical　framework　for　predicting　the　entire　stress-strain　relations　is　developed,　and　its　accuracy　is　verified　by　the　tensile　test　results　of　GNP/Ti6Al4V　nanocomposites.　The　effects　of　the　micromechanical　variables　including　volume　fraction　and　stiffness　of　interphase,　as　well　as　geometrical　size　factor　(ratio　of　interphase　thickness　to　the　GNP　equivalent　diameter)　and　aspect　ratio　of　GNPs　on　the　maximum　strength　and　failure　strain　are　quantitatively　analyzed　to　demonstrate　how　the　strength　and　plasticity　of　nanocomposites　are　enhanced　concurrently.　This　work　provides　a　new　perspective　for　graphene/metal　nanocomposites　with　excellent　tensile　properties　by　optimizing　interfacial　characteristics.　©　2021　Elsevier　Ltd