2D　materials　with　Dirac　cones,　which　show　a　linear　band　character　near　the　Fermi　level,　exhibit　many　novel　properties.　Herein,　based　on　first-principles　calculations,　the　2D　phosphorus　carbide　(　PC　5　)　monolayer　is　studied　systematically.　The　stability　is　examined　by　calculating　the　formation　energy,　phonon　dispersion,　and　elastic　constants　as　well　as　by　performing　ab　initio　molecular　dynamics　(AIMD)　simulations.　Due　to　the　similarity　of　its　structure　to　that　of　graphene,　one　Dirac　cone　is　exactly　located　at　the　Fermi　level,　which　is　very　robust　against　external　biaxial　and　uniaxial　strains.　Treating　the　PC　5　monolayer　as　graphene　with　doped　P　atoms　along　the　armchair　direction,　a　3　N　rule　is　found　similar　to　that　of　graphene　nanoribbons　with　armchair　edges.　These　physical　properties　make　the　PC　5　monolayer　a　promising　2D　material　for　emerging　electronics　applications.