TiO₂ photocatalyst has some disadvantages, such as wider band gap, high electron-hole recombination rate, etc. Therefore, a lot of research work focused on the modification of TiO₂ photocatalyst has been carried out at home and aboard. Some modification methods of TiO₂ photocatalyst, e.g. noble metal deposition, element doping (metal ion doping, non-metal doping, and co-doping), compound semiconductor, photosensitization, and surface acidification, as well as their mechanisms are summarized. Among them, the response wavelength of TiO₂ shows a red-shift after non-metal doping or co-doping, at the meanwhile, UV response of TiO₂ is preserved, therefore, the superimposition of good process effect is realized. The future direction of photocatalytic study is looked into, giving consideration to the production cast, keeping the stability of TiO₂ in complex environment, and increasing recovery rate of TiO₂.