Abstract: TiO2/SiO2 were prepared by the chemical modification reaction on SiO2, then the supported coupled semiconductors (MoO3, ZnO)-TiO2/SiO2 were prepared by isovolumic impregnating TiO2/SiO2. The surface structure, chemical adsorption capabilities, photon absorption properties and photocatalytic behaviors of MoO3-TiO2/SiO2 and ZnO-TiO2/SiO2 were systematically investigated by the techniques of X-ray differaction (XRD), BET, temperature programmed reduction (TPR), UV-Vis DRS, IR and temperature programmed desorpsion (TPD). The surface species of MoO3-TiO2/SiO2 and ZnO-TiO2/SiO2, comprising Mo—O—Ti and Zn—O—Ti bonds respectively, have the quantum size effects due to the supports interaction. The supported coupled semiconductors MoO3-TiO2/SiO2 exhibits higher photocatalytic activity than ZnO-TiO2/SiO2, because chemisorption property of CH4 and utilization of the photo energy enhanced effectively when MoO3 was incorporated on TiO2/SiO2. CH3OH and H2 are produced by the gas-phase photocatalytic reaction of CH4 and H2O over MoO3-TiO2/SiO2 catalyst at 150℃ in a fixed-bed annular photoreactor, and the CH3OH selectivity is 87.3%.