Over　the　past　several　decades,　much　effort　has　been　applied　to　atmospheric　nitrogen　oxide　(NOx)　abatement.　The　current　techniques　require　high　energy　consumption　and　result　in　secondary　pollution.　Particularly,　the　removal　of　low　dose　(＜200　ppm)　of　NOx　has　been　very　challenging.　Though　graphitic　carbon　nitride　(g-CN),　an　eco-friendly　and　sustainable　material　was　tried　as　a　promising　metal-free　photocatalyst　for　NOx　abatement.　Herein,　a　one-step,　energy　efficient　calcination　approach　is　developed　to　prepare　amorphous　carbon　nitride　(ACN)　with　N3(C)-site　vacancies.　The　visible-light　responsive　range　is　expanded　and　the　activation　barrier　of　N(sic)O　triple　bonds　is　sharply　decreased　by　one　order　of　magnitude;　0.19　eV　when　compared　to　the　2.22　eV　of　g-CN.　These　modifications　allow　the　NOx　removal　efficiency　of　ACN　to　reach　57.1%　which　is　among　the　highest　in　visible　light.　The　unique　N3(C)-site　vacancies　are　well　maintained　after　photocatalytic　NO　oxidation,　which　shows　an　exceptional　structural　stability.　This　boosts　the　generation　of　singlet　oxygen　(O-1(2))　and　superoxide　radical　(O-center　dot(2)-)　for　complete　NO　removal.　This　study　sheds　light　on　the　active　site　design　and　photocatalytic　performance　enhancement　of　g-CN　based　materials　by　vacancy　engineering.