Core-shell photocatalyst TiO2/Fe3O4 particles were prepared by sol-gel technique. Intermediate SiO2 was then added to form the catalyst TiO2/SiO2/Fe3O4. The photocatalytic activities of the catalysts were investigated by changing the preparation conditions such as pH and the ratio of Fe3O4 and TiO2. The magnetic properties，crystal phase and morphology of the particles were characterized by XRD, FT-IR, VSM and TEM. The result showed that both TiO2/Fe3O4 and TiO2/SiO2/Fe3O4 photocatalyst had superparamagnetic property and relatively high photocatalytic activity. Decolourization rates of methylorange were up to 90% in 1 h and the photocatalytic degradation of TiO2/Fe3O4 and TiO2/SiO2/Fe3O4 belonged to first order kinetic reactions. The introduction of SiO2 layer had a significant effect on improving saturated magnetization, photocatalytic rate and recycling photocatalytic activity.