Due　to　rock　masses＇　nonlinear　failure　property,　it　is　inappropriate　to　investigate　the　stability　of　rock　slopes　using　the　traditional　SRM　(strength　reduction　method)　which　is　based　on　the　linear　MC　(Mohr-Coulomb)　failure　criterion.　To　conduct　3D　analysis　(three　dimensional)　of　rock　slopes,　we　propose　a　3D-NSRNMM　(3D　nonlinear　strength　reduction　numerical　manifold　method)　that　is　based　on　the　nonlinear　GHB　(Generalized　Hoek-Brown)　failure　criterion.　To　effectively　implement　the　proposed　3D-NSRNMM,　two　methods　are　adopted　to　convert　the　GHB　parameters　into　the　average　and　instantaneous　equivalent　MC　parameters.　With　the　proposed　3D-NSRNMM,　the　influences　of　different　types　of　equivalent　MC　parameters,　and　boundary　conditions　on　rock　slopes＇　stability　are　investigated.　The　numerical　results　assessed　from　the　proposed　3D-NSRNMM　indicate　that:　1)　boundary　conditions　will　significantly　influence　the　safety　factor　and　failure　mode　of　a　rock　slope　obtained　from　3D　analysis;　2)　the　safety　factor　from　two-dimensional　analysis　is　more　conservative　compared　with　3D　analysis;　3)　Furthermore,　safety　factors　based　on　the　instantaneous　equivalent　MC　parameters　are　very　close　to　those　based　on　the　average　equivalent　MC　parameters,　but　3D　rock　slopes＇　failure　modes　based　on　the　two　different　types　of　equivalent　MC　parameters　are　a　little　different　from　each　other.