To　investigate　the　debonding　behavior　of　carbon　fiber　reinforced　polymer　(CFRP)-concrete　interface　under　mixed-mode　loading　conditions,　a　damage　initiation　law　based　on　Mohr-Coulomb　strength　criterion　in　tension　side　and　parabola　strength　criterion　in　compression　side　was　proposed,　and　the　mixed-mode　coupled　constitutive　law　of　the　interface　was　established.　The　partial　derivatives　of　the　interfacial　stresses　on　the　relative　separations　were　derived,　thus　the　required　Jacobian　matrix　was　obtained　for　the　numerical　analysis.　The　proposed　model　was　validated　by　the　comparison　with　experimental　results　of　4　specimens　in　the　literature.　The　parametric　study　was　conducted　on　the　CFRP-concrete　interfacial　behavior,　the　influences　of　the　peel　angle,　the　weight　ratio　of　the　normal　and　tangential　separations,　the　normal　and　tangential　strength　ratio,　and　the　CFRP　plate　thickness　on　the　interfacial　failure　mode　were　analyzed.　The　results　show　that　the　mixed-mode　constitutive　model　can　accurately　predict　the　interfacial　debonding　failure　and　the　strain　distribution　of　the　CFRP　plate.　The　increase　of　the　peel　angle　can　significantly　reduce　the　ultimate　strength　and　steady-state　strength,　while　the　steady-state　strength　is　not　affected　by　the　weight　ratio,　the　strength　ratio　or　the　CFRP　plate　thickness.　Strain　variations　can　be　observed　on　the　top　surface　of　the　CFRP　plate　where　the　critical　failure　occurs　in　the　normal　direction.　The　interfacial　fracture　position　can　be　predicted　by　the　location　of　fluctuating　strains.　©　2022,　Editorial　Office　of　Journal　of　Building　Structures.　All　right　reserved.