Converting　CO2　into　carbonaceous　fuels　via　photocatalysis　represents　an　appealing　strategy　to　simultaneously　alleviate　the　energy　crisis　and　associated　environmental　problems,　yet　designing　with　high　photoreduction　activity　catalysts　remains　a　compelling　challenge.　Here,　combining　the　merits　of　highly　porous　structure　and　maximum　atomic　efficiency,　we　rationally　constructed　covalent　triazine-based　frameworks　(CTFs)　anchoring　copper　single　atoms　(Cu-SA/CTF)　photocatalysts　for　efficient　CO2　conversion.　The　Cu　single　atoms　were　visualized　by　high-angle　annular　dark-field　scanning　transmission　electron　microscopy　(HAADF-STEM)　images　and　coordination　structure　of　Cu-N-C-2　sites　was　revealed　by　extended　X-ray　absorption　fine　structure　(EXAFS)　analyses.　The　as-prepared　Cu-SA/CTF　photocatalysts　exhibited　superior　photocatalytic　CO2　conversion　to　CH4　performance　associated　with　a　high　selectivity　of　98.31%.　Significantly,　the　introduction　of　Cu　single　atoms　endowed　the　Cu-SA/CTF　catalysts　with　increased　CO2　adsorption　capacity,　strengthened　visible　light　responsive　ability,　and　improved　the　photogenerated　carriers　separation　efficiency,　thus　enhancing　the　photocatalytic　activity.　This　work　provides　useful　guidelines　for　designing　robust　visible　light　responsive　photoreduction　CO2　catalysts　on　the　atomic　scale.