p-n junction photocatalyst p-CaFe2O4/n-Ag3VO4 was prepared by ball milling Ag3VO4 in H2O doped with p-type CaFe2O4. The structural and optical properties of the photocatalyst were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and UV-vis diffuse reflection spectrum (DRS). The photocatalytic activity was evaluated by photocatalytic degradation of methylene blue (MB) under visible light irradiation. The results showed that the photocatalytic activity of the p-CaFe2O4/n-Ag3VO4 was higher than that of Ag3VO4. When the amount of doped p-CaFe2O4 was 2.0wt.% and the p-CaFe2O4/n-Ag3VO4 was ball milled for 12h. the photocatalytic degradation efficiency was 85.4%. Effect of ball milling time on the photocatalytic activity of the photocatalyst was also investigated. The mechanisms of the increase in the photocatalytic activity were discussed by the p-n junction principle. (C) 2009 Published by Elsevier B.V.