Abstract: Flower sphere-like Bi₂WO₆ and mesoporous carbon CMK-3/Bi₂WO₆ photocatalysts were synthesized by hydrothermal method, and then Ag/Bi₂WO₆ and Ag/CMK-3/Bi₂WO₆ were prepared via a photoreduction process in order to obtain the photocatalysts with high visible light activities. The as-prepared samples were characterized by ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), X-ray diffraction (XRD), transmission electron microscope(TEM), high resolution transmission electron microscope (HR-TEM) and scanning electron microscope (SEM). The photocatalytic activities of the samples were evaluated by the photodegradation of methylene blue (MB) under visible light irradiation. The mechanism for the enhancement of the photocatalytic activity of CMK-3 and Ag-loaded Bi₂WO₆ was also investigated. The results show that CMK-3 or Ag loading greatly improves the photocatalytic activity of Bi₂WO₆, the photocatalytic activity of Ag/CMK-3/Bi₂WO₆ photocatalyst is superior to the activities of CMK-3/Bi₂WO₆ and Ag/Bi₂WO₆ photocatalysts.