TiO2 sols modified by rare earth (RE) ions (Ce4+, Eu3+, or Nd3+) were prepared by coprecipitation-peptization method. The photocatalysis activity was studied by investigating the photodegradation effects of active brilliant red dye X-3B. It is found that TiO2 sols modified by Ce4+, Eu3+, or Nd3+ have the anatase crystalline structure, which are prepared at 70℃. All REn+-TiO2 sol samples have uniform nanoparticles with similar morphology, which are homogenously distributed in aqueous colloidal systems. The particle sizes are 10, 8, and 12 ran for Nd3+-TiO2, Eu3+-TiO2, and Ce4+-TiO2, respectively. The character of ultrafine and positive charge sol particles contributes to the good adsorption of X-3B dye molecule on the surface of titania (about 30% X-3B adsorption amount). Experimental results exhibit that REn+-TiO2 sol photocatalysts have the capability to photodegrade X-3B under visible light irradiation. Nd3+-TiO2 and Eu3+-TiO2 show higher photocatalytic activity than Ce4+-TiO2, which is due to the di The photocatalysis activity was studied by investigating the photodegradation effects of active brilliant red dye X-3B. It is found that TiO2 (Ce4 +, Eu3 +, or Nd3 +) was prepared by coprecipitation-peptization method sols modified by Ce4 +, Eu3 +, or Nd3 + have the anatase crystalline structure, which are prepared at 70 ° C. All REn + -TiO2 sol samples have uniform nanoparticles with similar morphology, which are homogenously distributed in aqueous colloidal systems. The particle sizes are 10, 8 and 12 ran for Nd3 + -TiO2, Eu3 + -TiO2, and Ce4 + -TiO2, respectively. The character of ultrafine and positive charge sol particles contributes to the good adsorption of X-3B dye molecule on the surface of titania (about 30% X-3B deposit amount). Experimental results exhibit that REn + -TiO2 sol photocatalysts have the capability to photodegrade X-3B under visible light irradiation. Nd3 + -TiO2 and Eu3 + -TiO2 show higher photocatalytic activity than Ce4 + -TiO2, whi ch is due to the di