Solar-driven reduction of CO2 and H2O into fuels is a promising approach for addressing global warming and energy crisis. Herein, Cu+ doped W18O49 nanowires were prepared by a facile solvothermal method and applied in photocatalytic reduction of CO2. The composition and structure of pristine and Cu+ doped W18O49 samples have been characterized. It was found that the morphology of W18O49 nanowires was changed with increasing amounts of dopant. The photocatalytic CO2 reduction activity of W18O49 nanowires and the Cu+ doped W18O49 samples were evaluated using H2O as reducing agent. The strategy of Cu+ doping not only could affect the band edge position and the surface wettability, but also influenced separation of the photogenerated electron-hole pairs. It was found that Cu+ doping could introduce oxygen vacancy and change the conduction edge to a more negative position for W18O49 nanowires, which might be beneficial for the activation of CO2 and promote the following CO2 reduction. Furthermore, the higher separation efficiency of photogenerated electron-hole pairs with Cu+ doping could contribute to the CO2 photoreduction enhancement. In addition, the Cu+ doped W18O49 nanowires (Cu-W18O49-0.005) presented a relatively poor hydrophilic property, which might be beneficial for the adsorption of CO2 molecules and contribute to its superior photocatalytic CO2 reduction capability.