MoO3/MoS2 composite structure was prepared by hydrothermal and illumination method. The morphology, structure and photochromic properties of the samples were characterized by TEM, XRD, XPS and UV-Vis spectrophotometer. The samples show nanowire bundle structure. The color of the sample is yellow with the ratio of Na2MoO4·2H2O to C2H5HS is 1∶3. While the color of the samples are blue when the ratio of Na2MoO4·2H2O to C2H5HS is below 1∶3. The prepared samples have photochromic effect. The photochromic property of MoO3/MoS2 is the best with the ratio of Na2MoO4·2H2O to C2H5HS is 1∶2. The excellent photochromic efficiency is attributed to the appropriate band structure of MoO3/MoS2 composite structure, which can effectively separate photogenerated carriers and suppressed the recombination of electrons and holes.