Bi25FeO40 powders have successfully been synthesized by simple hydrothermal method. The effect of the concentration of mineralizer and stoichiometry on the prepared samples was investigated. With the UV-Vis spectra, Bi25FeO40 powders have a broad absorption band in the range of 400-600 nm and a good visible-light-response ability. Photo-catalytic activity of Bi25FeO40 powders was evaluated by the degradation of methyl violet solution under UV-Vis light irradiation, which is found that Bi25FeO40 is efficient for photo-degradation of the methyl violet due to its own crystal structure.