Abstract: Silica，diatomite，and opal loaded nano-sized TiO2 composites were prepared by hydrolysis precipitation method.The composite materials were characterized by means of SEM and XRD，and photocatalytic properties thereof were evaluated by the photocatalytic decolorization rate of Rhodamine B solution.Results showed:a large amount of TiO2 was loaded on the surface of the composite material，and the main type was anatase；and the average particle sizes of TiO2 were 14.6 nm，25.7 nm，and 22.9 nm on the surfaces of silica，diatomite，and opal respectively.The best preparation conditions of the three kinds of composites of TiO2/silica，TiO2/diatomite，and TiO2/opal were respectively：700 ℃ calcined for 2 h，and the loading of TiO2 was 30%；700 ℃ calcined for 2 h，and the loading of TiO2 was 20%；600 ℃ calcined for 2 h，and the loading of TiO2 was 20%.The degradation rates of three kinds of composite materials on the degradation of Rhodamine B for 15 min were 98.6%，97.4%，and 87.7%，respectively.

Key words: nano-sized TiO2, compound material, photocatalysis, degradation