Abstract: In order to solve the problem of easy agglomeration of TiO₂ and wide band gap, and improve the photocatalytic degradation rate of Congo Red (CR). BiOCl/TiO₂/montmorillonite composites were prepared by hydrolysis and sol-gel methods. Photocatalytic experiments were carried out with Congo Red dye as the target degradation product. The effects of sol pH, mass concentration of montmorillonite suspension, roasting temperature, roasting time and Bi/Ti molar ratio on the photocatalytic activity of the composites were studied, and the composites were characterized by X-ray diffractometer (XRD) and Ultraviolet-visible diffuse reflection spectrum (UV-Vis DRS). The results showed that the BiOCl/TiO₂/montmorillonite composite had high photocatalytic activity when the the pH of the sol was 4, the mass concentration of the montmorillonite suspension was 1%, the roasting temperature was 600℃, the roasting time was 2 h, and the molar ratio of Bi/Ti was 20%. The removal rate of Congo Red reached 94.04%. The composite TiO₂ exists in the form of anatase crystal phase. The addition of both montmorillonite and BiOCl inhibited the growth of TiO₂ crystals. The formation of heterojunction between BiOCl/TiO₂ reduced the band gap from 2.89 eV to 2.61 eV, which enhanced the light absorption capacity of composites.