Accurate　and　efficient　contact　detection　between　polygons　or　polyhedra　is　a　critical　challenge　in　discontinuous　numerical　methods.　The　contact　theory　offers　a　rigorous　framework　for　addressing　contact　problems.　However,　its　broader　practical　application　is　limited　by　high　computational　costs.　This　inefficiency　arises　from　the　calculation　of　the　entrance　block　for　all　vertex-edge　pairs,　many　of　which　ultimately　do　not　contribute　to　contact　detection.　To　overcome　this　limitation,　we　propose　a　novel　contact　detection　algorithm　based　on　the　local　entrance　block　(LEB)　method.　The　proposed　LEB　method　constructs　entrance　blocks　from　only　partial　geometric　elements　identified　by　the　multi-cover　neighbor　search　(MNS)　method,　which　automatically　filters　potential　contact　geometries　in　the　rough　search　phase.　By　focusing　on　local　geometry,　the　LEB　method　substantially　reduces　unnecessary　computations　without　compromising　detection　accuracy.　This　algorithm　was　implemented　in　the　2D　DDA　and　validated　through　five　rock　engineering　simulation　cases.　Results　demonstrate　that　the　LEB　method　accelerates　contact　detection　while　maintaining　the　robustness　and　precision　of　contact　theory.　These　findings　highlight　the　potential　of　contact　theory　for　large-scale　and　complex　discontinuous　simulations.