Abstract: TiO2/SiO2/Fe3O4 composite photocatalyst was successfully prepared by the sol–gel method with magnetic core SiO2/Fe3O4 as matrix. The samples were characterized with AFM and XRD. The conditions of photocatalytic degradation such as pH，the amounts of photocatalyst, the initial concentration of bromamine acid, etc, were studied in the decolorization of bromamine acid. The results showed that when solution pH was 4.0, the amount of TiO2/SiO2/Fe3O4 was 2.0g/L, the initial concentration of bromamine acid was 30mg/L, illumination time was 30min, the decolorization ratio and the removal rate of COD was 96.2% and 85.1% respectively. Within the range of the initial concentration of bromamine acid, the photochemical decoloration reaction was expressed as first order kinetics, and the effect of initial concentration of bromamine acid on rate constant was: lnk =–0.171 lnc0–2.360. After four times of use, the TiO2/SiO2/Fe3O4 still had good photocatalytic activity and high recovery efficiency.