Targeted　electron　transfer　to　catalytically　active　site　for　CO2　reduction　is　promising　for　enhancing　the　efficiency　of　artificial　photosynthesis.　Here,　we　demonstrate　a　design　of　an　alkyl-linked　heterostructure　composing　of　TiO2　and　a　Cu-porphyrin-based　covalent　organic　framework　(TiO2@CuPorTT-COF)　for　the　photoreduction　of　CO2　with　H2O.　Through　specific　coordination　effect,　the　alkyl　chain　bridges　TiO2　and　Cu　moiety　in　COF.　Upon　light　illumination,　the　photoinduced　electrons　in　TiO2　can　be　directionally　transported　across　the　interface　along　the　alkyl　chain　to　the　Cu　active　sites　to　reduce　adsorbed　CO2,　while　the　left　holes　are　consumed　by　the　H2O　oxidation,　enhancing　the　spatial　separation　and　utilization　of　electron-hole　pairs.　Accordingly,　the　TiO2@CuPorTT-COF　enables　remarkably　superior　catalytic　activities　over　the　counterpart　without　the　alkyl　bridge　for　electron　transfer　with　5　times　of　CO　production　rate.　An　apparent　quantum　efficiency　of　0.455%　at　380　nm　is　achieved.　Moreover,　a　dynamic　evolution　of　Cu　active　site　for　CO2　reduction　is　revealed,　which　can　be　promoted　by　the　targeting　electron　transport　approach.　This　work　provides　a　targeted　electron　transport　strategy　for　constructing　photocatalysts.