The washed and dried porous silica gel was soaked in water glass of moderate viscosity, then mixed with nanometer TiO 2, stired until TiO 2 has been uniformly distributed on the porous silica gel. After dried naturally, it was calcined at 300 ℃ for 1 h to give the immobilized nanometer TiO 2 which was mechanically and chemically stable, and can be reused. Under the illumination of high pressure Hg lamp, the X 3B dye could be degraded almost quantitatively(98%) in a solution containing the photocatalyst, Fe 3+ and H 2O 2 with bubbling of air.