The　low　light　absorption　capacity,　fast　recombination　of　photogenerated　carriers　and　slow　H+　reduction　kinetics　of　carbon　nitride　severely　limit　its　application　in　photocatalytic　research.　What＇s　more,　the　challenge　remains　to　efficiently　utilise　photogenerated　electrons.　In　this　work,　sulfur　(S)　self-doped　carbon　nitride　(SCN)　was　formed　by　thermal　polymerisation,　and　the　introduction　of　S　stimulated　the　electron　delocalisation　of　the　active　site　and　optimised　the　absorption　of　visible　light　by　the　carbon　nitride.　The　introduction　of　defects　and　cyano　(-C　N)　groups　optimises　the　surface　atomic　and　electronic　structure　of　SCN,　enhances　photogenerated　electron　trapping　and　greatly　suppresses　charge　recombination.　The　n-pi*　electron　jump　of　the　lone　pair　of　electrons　at　the　defect　site　gives　rise　to　a　new　absorption　band　that　broadens　the　response　to　visible　light.　The　H-2　evolution　rate　of　SCNV　under　visible　light　reached　3437　mu　mol　g(-1)　h(-1),　which　was　about　3.0　times　higher　than　that　of　SCN　(1148　mu　mol　g(-1)　h(-1)).　Density　Functional　Theory　(DFT)　calculations　further　show　that　the　introduction　of　defects　and　-C　N　lowers　the　energy　barrier　of　*H,　enhances　carrier　separation,　and　forms　an　electron-rich　structure,　which　effectively　promotes　the　utilisation　of　photogenerated　electrons　and　photocatalytic　H2　evolution　efficiency.