The dispersion property of modified nano-TiO₂ particles and its antibacterial properties on cotton fabrics were studied. The nano-TiO₂ particles were modified with reactive groups (such as hydroxyl groups, amino groups and silica groups). The modified nano-TiO₂ particles were characterized by particle size analyzer, Fourier transform-infrared spectroscopy and transmission electron microscopy. Besides, the chemical load technology of optimizing the nano-TiO₂ on the textile fiber combined with fiber by grafting and cross-linking was studied. The results showed that the stability of nano-TiO₂ sol was related to the concentration of the modifier and the pH values of the system. The washing fastness and the antibacterial property of the fabric treated by modified nano-TiO₂ had been increased and the antibacterial property of treated fabric was also related to the concentration of the modifier. By determining the fiber’s crystallinity, as well as the fabric’s breaking strength and tear strength, the influence of the modified nano-TiO₂ photocatalyst on the structural properties of cotton fiber was discussed.