Single　crystal　diamond　(SCD)　holds　great　potential　for　next-generation　integrated　circuits.　However,　its　high　hardness　and　chemical　inertness　present　significant　challenges　to　polishing　with　high　material　removal　rates　and　ultra-smooth　surfaces.　This　study　investigates　the　generation　and　removal　mechanisms　in　nitrogen　plasma-assisted　polishing　of　SCD　through　ReaxFF　molecular　dynamics　simulations　and　polishing　experiments.　Simulation　results　reveal　that　sp(2)　hybridized　modified　structures　form　on　the　SCD　surface　at　an　optimal　plasma　temperature　of　2000-3000　K.　These　structures　facilitate　atom　removal,　reducing　the　surface　friction　coefficient　by　28.74%.　After　polishing,　the　nitrogen　content　on　the　SCD　surface　returned　to　its　original　level,　indicating　that　the　modified　surface　layer　was　easily　removed.　Nitrogen　plasma-assisted　polishing　transforms　the　stable　sp(3)　hybridized　structure　of　SCD　into　a　more　easily　removable　sp(2)　hybridized　form.　A　selective　conjugated　bond-breaking　effect　is　proposed　to　explain　the　removal　mechanism,　in　the　modified　structure,　certain　bonds　within　the　conjugated　rings　exhibit　a　bond　order　of　1,　making　them　more　susceptible　to　breakage.　The　resulting　carbon　dangling　bonds　readily　bond　with　abrasive　particles,　thereby　facilitating　material　removal.　The　proposed　mechanism　offers　a　new　perspective　for　enhancing　both　efficiency　and　surface　quality　in　diamond　polishing　processes.