The mixed-phase TiO 2 photocatalysts with different anatase/rutile/brookite ratios and high specific surface area (157–218m 2 /g) were prepared by hydrothermal method at 100°C and the effect of rutile content in TiO 2 on the BET surface area, light absorption and separation efficiency of photogenerated charge carriers was studied and correlated to the photocatalytic activity of TiO 2 . Rutile content increased from 0% to 100% by increasing the amount of TiCl 4 in aqueous phase and the initial pH value of reaction solution played an important role in the phase composition of TiO 2 . The photocatalytic mechanism of mixed-phase TiO 2 was discussed.