A　Polyaniline　(PANI)　assembled　Au/TiO2　catalyst　(Au/TiO2-PANI)　was　prepared　by　deposition-precipitation　with　the　assistance　of　in-situ　polymerization　assistance,　and　was　performed　for　oxidizing　CO　in　H2-rich　stream　under　visible　light　irradiation.　It　is　found　that　the　as-prepared　Au/TiO2-PANI　exhibited　a　higher　activity　of　CO　preferential　oxidation　(PROX)　than　the　Au/TiO2　without　PANI　decoration　at　room　temperature　under　visible　light　irradiation.　Based　on　the　results　of　structure　characterization,　photo-Absorbance,　photo-electrochemical,　electron　paramagnetic　resonance,　and　adsorbing　CO　and　H2　of　Au/TiO2-PANI,　it　is　proposed　that　the　photo-excited　electrons　of　PANI　could　transfer　to　TiO2　accompanied　by　suppressing　the　transfer　of　excited　electrons　induced　by　the　localized　surface　plasmon　resonance　of　Au　nanoparticles　to　TiO2,　resulting　in　the　increases　in　surface　electron　densities　of　both　Au　and　TiO2　sites.　This　will　promote　the　activation　of　CO　adsorbed　at　Au　sites　and　the　formation　of　O2-　species　at　TiO2　sites,　and　then　the　oxidation　of　CO.　Meanwhile,　the　protonation　of　N　atoms　in　PANI　could　cause　a　spillover　of　the　dissociative　H　at　Au　sites　into　PANI,　resulting　in　the　suppression　of　H2　oxidation.　©　2014,　Hydrogen　Energy　Publications,　LLC.　Published　by　Elsevier　Ltd.　All　rights　reserved.