The novel visible-light-driven Bi2WO6 photocatalyst with orthorhombic structures was synthesized via a reverse microemulsion method. The as-prepared Bi2WO6 samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The photocatalytic activity of the Bi2WO6 powders was determined by degradation of methyl orange molecules in water under visible light irradiation (λ>400nm). The results revealed that the particle and crystallite sizes of the Bi2WO6 powders significantly depended on the synthesis temperature of the reverse microemulsion solutions. The photocatalytic tests indicated that the synthesis temperature also can significantly affect the visible light driven photocatalytic activities.