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 superparamagnetic property and relatively high photocatalytic activity. Decolourization rates of methylorange 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.