This　study　presents　a　three-dimensional　numerical　model　based　on　the　Hashin　damage　criteria　to　assess　the　seismic　performance　of　Carbon　Fiber　Reinforced　Polymer　(CFRP)-strengthened　Reinforced　Concrete　(RC)　shear　walls,　accurately　capturing　the　rupture　of　CFRP　strips.　The　effectiveness　of　various　CFRP-concrete　interface　modeling　methods　in　capturing　CFRP　debonding　was　initially　discussed.　A　series　of　numerical　simulations　were　then　conducted　to　investigate　the　combined　effects　of　the　CFRP　ratio　and　the　horizontal　reinforcement　ratio　on　the　seismic　behavior　of　CFRP-strengthened　shear　walls.　The　results　indicate　that　an　increase　in　the　CFRP　ratio　reduces　the　failure　degree　of　shear　walls,　as　the　shear　damage　shifts　progressively　from　the　concrete　and　horizontal　reinforcement　to　the　CFRP　strips.　However,　an　increase　in　the　horizontal　reinforcement　ratio　counterproductively　weakens　the　shear-strengthening　effect　provided　by　the　CFRP　strips.　To　specifically　evaluate　the　shear　contribution　of　the　CFRP　strips,　a　novel　coefficient　was　proposed　and　validated,　capturing　the　combined　effect　of　the　CFRP　ratio　and　the　horizontal　reinforcement　ratio　on　the　shear　contribution　of　the　CFRP　strips.　This　coefficient　provides　a　quantitative　measure　to　optimize　the　reinforcement　design　of　RC　shear　walls.