Photocatalytic paint was prepared by adding Fe-doped TiO2 nanocrystalline powders into self-engineered oxidation-resistant latex paint system. The UV-Vis diffuse reflectance spectroscopy was used to characterize the light absorption properties of the paint. The colony counting method was used to study photocatalytic sterilization ratio of E. coli under visible light irradiation. Effects of the kinds and amounts of TiO2 powders added in the paint on the sterilization ratio under visible light irradiation with fixed relative humidity were systematically investigated. The UV-Vis diffuse reflectance spectroscopy indicates that the absorption thresholds of the Fe-doped TiO2 paint have red-shifted into visible light region. The antibacterial experiment results show that the sterilization ratio of E. coli can exceed more than 99% in less than 4 hours under 400-lux-visible light irradiation under RH of 55%.