Solar-driven　photoreduction　of　CO2into　valuable　fuels　offers　a　sustainable　technology　to　relieve　the　energy　crisis　as　well　as　the　greenhouse　effect.　Yet　the　exploration　of　highly　efficient,　selective,　stable,　and　environmental　benign　photocatalysts　for　CO2reduction　remains　a　major　issue　and　challenge.　The　interfacial　engineering　of　heterojunction　photocatalysts　could　be　a　valid　approach　to　boost　the　efficiency　of　the　catalytic　process.　Herein,　we　propose　a　novel　covalent　organic　framework/metal　organic　framework　(COF/MOF)　heterojunction　photocatalyst,　using　olefin　(C=C)　linked　covalent　organic　framework　(TTCOF)　and　NH2-UiO-66　(Zr)　(NUZ)　as　representative　building　blocks,　for　enhanced　CO2reduction　to　CO.　The　optimized　TTCOF/NUZ　exhibited　a　superior　CO　yield　(6.56　μmol　g-1h-1)　in　gas-solid　system　when　irradiated　by　visible　light　and　only　with　H2O　(g)　as　weak　reductant,　and　it　was　4.4　and　5　times　higher　than　pristine　TTCOF　and　NUZ,　respectively.　The　photogenerated　electrons　transfer　route　was　proposed　to　follow　the　typical　step-scheme　(S-scheme),　which　was　affirmed　by　XPS,　in　situ　XPS　and　EPR　characterizations.　The　boosting　CO2photoreduction　activity　could　be　credited　to　the　special　charge　carrier　separation　in　S-scheme　heterojunction,　which　can　accelerate　photogenerated　electrons　transportation　and　improve　the　redox　ability　at　the　interface.　This　work　paves　the　way　for　the　design　and　preparation　of　novel　COF/MOF　S-scheme　heterostructure　photocatalysts　for　CO2reduction.　©　2022　American　Chemical　Society.　All　rights　reserved.