To　investigate　the　stability　of　a　soil-rock-mixture　(SRM)　slope　subjected　to　sequential　excavation,　two　modifications　are　made　to　the　numerical　manifold　method　(NMM).　One　modification　is　the　implementation　of　sequential　excavation　algorithms　including　an　algorithm　to　find　the　excavated　manifold　elements　and　an　algorithm　named　as　＂manifold　element　birth　and　death＂　to　remove　the　excavated　manifold　elements　in　the　excavation　simulation.　The　other　modification　is　the　implementation　of　an　improved　shear　strength　reduction　technique　to　evaluate　the　stability　of　a　slope,　as　well　as　to　obtain　the　factor　of　safety　(FOS).　In　this　technique,　apart　from　the　shear　strength　parameters,　the　Poisson＇s　ratio　upsilon　is　also　adjusted　for　the　purpose　of　eliminating　the　spurious　plastic　deformation　that　may　happen　in　the　deep　areas　of　the　slope.　Two　criterions　including　the　NC　criterion　(Non-convergence　criterion)　and　DPZ　criterion　(The　criterion　based　on　the　distribution　of　plastic　zones)　are　used　to　define　the　critical　equilibrium　state　of　the　slope.　With　the　improved　NMM,　three　numerical　examples　including　a　homogeneous　slope　under　one　step　of　excavation,　a　slope　under　three　steps　of　excavation　and　a　SRM　slope　under　two　steps　of　excavation　are　solved.　The　simulation　results　show　that:　(1)　the　improved　NMM　is　able　to　accurately　simulate　the　excavation　process　of　slopes,　and　predict　the　FOSs　of　slopes;　(2)　the　FOSs　based　on　the　NC　criterion　are　usually　greater　than　or　equal　to　those　based　on　the　DPZ　criterion;　(3)　it　is　very　difficult　to　form　a　slipping　surface　passing　from　the　toe　of　the　SRM　slope　to　the　top　of　the　SRM　slope;　(4)　rock　blocks　have　some　positive　effects　on　the　stability　of　a　SRM　slope.