The　shear　band　due　to　strain　localization　is　deemed　a　strong　discontinuous　plane　in　this　study,　and　simulated　by　the　numerical　manifold　method　(NMM).　The　SMP　(Spatially　Mobilized　Plane)　criterion　is　incorporated　into　the　Drucker-Prager　(DP)　model　by　the　transformed　stress　(TS)　method.　The　constitutive　integration　of　plasticity　is　carried　out　on　the　new　yielding　surface　with　the　tensile　part　being　cut　off,　leading　to　a　mixed　complementarity　problem　(MiCP).　The　Gauss-Seidel　based　projection　contraction　(GSPC)　algorithm　is　invoked　to　solve　the　MiCP.　In　NMM,　the　cohesion　is　a　constant　when　the　contact　is　in　slipping　state.　This　study　modifies　the　cohesion　so　that　the　decaying　of　cohesion　could　be　reflected　with　the　growth　of　the　sliding.　To　accelerate　the　convergence,　the　contact　stiffness　matrix　in　open　state　is　proposed　to　be　constructed　in　a　new　way　in　this　paper.　The　NMM　formulation　for　solving　the　strain　localization　problem　is　derived　in　this　study.　The　displacement　controlled　method　is　extended　to　the　material　nonlinearity　accompanied　with　contact　problem.　Two　examples,　including　the　soil　block　and　soil　slope　under　compression,　have　been　studied　to　verify　the　efficiency　of　the　proposed　method　in　simulating　the　process　of　shear　band　evolution.