A series of Y/TiO2 nanoparticles (NPs) were synthesized via sol-gel method. The crystal structures, morphologies and chemical properties were characterized using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). We investigated the effects of different doping amounts of Y on the reaction of CO2 photoreduction. The results shown that 0.1 wt.%Y/TiO2 (0.1YT) performed the highest photocatalytic activity, which yielded 384.62 µmol/g∙cat. formaldehyde after 6 h of UV illumination.