TiO2/SiO2　were　prepared　by　the　chemical　modification　reaction　on　SiO2,　then　the　supported　coupled　semiconductors　(MoO3,　ZnO)-TiO2/SiO2　were　prepared　by　isovolumetric　impregnating　TiO2/SiO2.　The　surface　structures,　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　diffraction　(XRD),　BET,　temperature　programmed　reduction　(TPR),　UV-Vis　DRS,　IR　and　temperature　programmed　desorption　(TPD).　The　surface　species　of　MoO3-TiO2/SiO2　and　ZnO-TiO2/SiO2,　comprising　Mo-O-Ti　bonds　and　Zn-O-Ti　bonds　respectively,　have　the　quantum　size　effects　due　to　the　supports　interaction.　The　supported　coupled　semiconductors　MoO3-TiO2/SiO2　exhibit　higher　photocatalytic　activity　than　ZnO-TiO2/SiO2,　because　chemisorption　property　of　CH4　and　utilization　of　the　photo　energy　enhance　effectively　when　MoO3　is　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°C　in　a　fixed-bed　annular　photoreactor,　and　the　CH3OH　selectivity　is　87.3%.