Abstract: The recent research progress of nano TiO₂ co-doping photocatalysts was reviewed.The action mechanism of nano TiO2 photocatalyst was described.From the promotion of TiO₂ visible light response，inhibiting the recombination of electrons and holes，causing lattce defects，increasing oxygen vacancies，and improving TiO₂ photocatalytic surface hydroxyl content etc.，the mechanism of nano TiO₂ photocatalyst doping modification was explained.The influences of different ions co-doping forms，such as nonmetal/nonmetal，nonmetal/metal，and metal/metal，on the photocatalytic performance of titanium dioxide photocatalyst were compared and analyzed.Finally，the suggestions for future research were proposed for photocatalytic materials.

Key words: co-doping, nano TiO₂, photocatalyst