The RE doped TiO2 was prepared by sol-gel method, the structure and shape were characterized by X-ray diffraction and FE-SEM. The photocatalytic activities were evaluated by degradation of chloramine phosphorus. The influence of variant doping amount of RE, different annealing temperature, original concentration, and original pH value of solution were analyzed. The results show that the doping with optimum RE can restrain the transform of anatase structure to rutile structure and the growth of crystal, and improve the photocatalytic efficiency. The optimal doping of La^3＋ is 0.5%, and that of Ce^3＋ is 1%. The best conditions are as follows： annealing temperature 500℃, and original concentration 20 mg/L. Acidic and alkaline conditions are preferred to neutral condition in the results of degradation.