The　low　specific　surface　area　and　low　charge　transfer　efficiency　of　conventional　graphite　carbon　nitride　(g-C3N4)　are　the　main　obstacles　to　its　application　in　photocatalytic　CO2　reduction.　In　this　paper,　graphite　carbon　nitride　was　protonated　by　phosphoric　acid　(H3PO4),　and　a　new　few-layer　porous　carbon　nitride　was　prepared　by　intercalation　polymerization　with　doping　bimetal　in　the　cavity　of　g-C3N4.　Under　visible　light　irradiation,　the　CO　formation　rate　of　Co/Ni　co-doped　g-C3N4　can　reach　13.55　μmol　g−1　h−1,　which　was　3.9　times　higher　than　that　of　g-C3N4　(3.49　μmol　g−1　h−1).　The　density　functional　theory　(DFT)　calculations　showed　that　the　addition　of　Co　and　Ni　in　the　cavity　of　g-C3N4　can　induce　bimetallic　synergistic　regulation　of　the　electronic　structure,　thus　improving　the　separation　efficiency　of　charges　and　visible　light　capture　ability　of　g-C3N4.　Our　work　has　great　reference　value　for　designing　and　synthesizing　novel　bimetallic　co-doped　g-C3N4　photocatalytic　materials.　©　2022