Two-dimensional　(2D)　materials　demonstrate　promising　potential　as　high-efficiency　photocatalysts.　However,　the　intrinsic　limitations　of　aluminum　nitride　(AlN),　such　as　inadequate　oxidation　capacity,　a　high　carrier　recombination　rate,　and　limited　absorption　of　visible　light,　pose　considerable　challenges.　In　this　paper,　we　introduce　a　novel　co-doping　technique　with　dysprosium　(Dy)　and　carbon　(C)　on　a　2D　AlN　monolayer,　aiming　to　enhance　its　photocatalytic　properties.　Our　first-principles　calculations　reveal　a　reduction　in　the　bandgap　and　a　significant　enhancement　in　the　visible　light　absorption　rate　of　the　co-doped　Al24N22DyC2　structure.　Notably,　the　distribution　of　the　highest　occupied　molecular　orbital　and　the　lowest　unoccupied　molecular　in　proximity　to　Dy　atoms　demonstrates　favorable　conditions　for　carrier　separation.　Theoretical　assessments　of　the　hydrogen　evolution　reaction　and　oxygen　evolution　reaction　activities　further　corroborate　the　potential　of　Al24N22DyC2　as　a　competent　catalyst　for　photocatalytic　reactions.　These　findings　provide　valuable　theoretical　insights　for　the　experimental　design　and　fabrication　of　novel,　high-efficiency　AlN　semiconductor　photocatalysts.　A　novel　Dy,　C　co-doped　material　on　2D　AlN　monolayer　is　introduced.　DFT　calculations　show　that　the　bandgap　of　Al24N22DyC2　decreases,　absorption　rate　of　visible　light　and　catalytic　activities　of　HER　and　OER　increases　significantly.