Cobalt-doped titania (Co-TiO2) nanomaterials were synthesized by the sol-gel method at different calcination temperatures. Using Escherichia coli (a), Staphylococcus aureus (b) and Candida albicans (c) as target strains, the antibacterial activity in visible light of the nanomaterials were studied. Co-TiO2 nanomaterials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectrum (FT-IR) and X-ray photoelectron spectroscopy (XPS). The Co ions in the Co-TiO2 nanomaterial exist in the form of CoTiO3 phase. The antibacterial properties of Co-TiO2 nanomaterials on E. coli (a), S. aureus (b) and C albicans (c) were investigated with the oscillating flask method and the inhibition zone method. The nanomaterials calcined at 600 degrees C exhibit excellent antibacterial activity. The bacteriostatic rates for E. coli, S. aureus and C. albicans reached 99.5%, 91.3% and 93.4% respectively. The diameters of the antibacterial rings were up to 36 mm, 37 mm, 30 mm respectively, and the clarity of the ring was dear. The antibacterial properties of Co-TiO2 nanomaterials were compared with those of traditional silver sol, zinc oxide sol and Zn-doped TiO2 nanomaterials The mechanism of the influences of Co ions doping on the antibacterial activity of TiO2 nanomaterials was also discussed. The doping of Co ions inhibits the particle size of the antibacterial agent and extends the photocatalytic response range, thereby improving the photocatalytic performance of the antibacterial agent. (C) 2020 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.