A　Ru/TiO(2-x)Nx　catalyst　was　prepared　by　impregnation-reduction　method　with　loading　Ru　on　the　nitrogen　doped　TiO2　support.　This　catalyst＇s　performance　for　CO2　methanation　was　evaluated　under　visible　light　irradiation　(435nm　<　λ　<　465　nm)　or　not,　which　was　compared　with　that　of　Ru/TiO2　catalyst.　It　was　found　that　Ru/TiO(2-x)Nx　exhibits　a　better　catalytic　activity　than　Ru/TiO2　under　visible　light　irradiation　or　not,　and　the　promoted　effect　of　visible　light　on　the　former　is　much　more　significant　than　that　on　the　latter＇s.　After　comparing　the　results　of　chemisorption,　temperature-programmed　surface　reaction,　X-ray　Photoelectron　spectroscopy　and　photocurrent　tests　over　Ru/TiO(2-x)Nx　and　Ru/TiO2,　it　was　found　that　the　photo-assisted　role　on　Ru/TiO(2-x)Nx　mainly　comes　from　two　cases:　(i)　The　TiO(2-x)Nx　itself　is　prone　to　adsorb　CO2　and　its　activation　into　the　CO　species　(as　the　intermediates　of　CO2　methanation　reaction),　which　visible　light　can　further　promote　the　process　by　forming　much　more　significant　oxygen　vacancies　over　TiO(2-x)Nx.　(ii)　The　photo-generated　electrons　of　TiO(2-x)Nx　induced　by　visible　light　can　transfer　to　the　Ru　nanoparticles,　resulting　in　the　increase　in　the　surface　electron　density　of　Ru　and　then　the　promoted　adsorption　and　activation　of　CO2.　For　Ru/TiO2,　TiO2　itself　cannot　transform　the　adsorbed　CO2　into　the　CO　intermediates,　which　resulted　in　a　lower　thermo-catalytic　activity　for　CO2　methanation.　Under　visible　light　irradiation,　the　extrinsic　excitation　of　TiO2　cannot　formation　of　new　surface　oxygen　vacancies　at　TiO2,　but　the　photo-generated　electrons　can　transfer　from　TiO2　to　Ru,　which　resulted　in　the　increase　of　surface　electron　density　and　then　the　promoted　adsorption　and　activation　of　CO2　at　Ru　sites.　Thus,　a　weaker　photo-assisted　effect　for　catalyzing　CO2　methanation　can　occur　on　Ru/TiO2.　©　2016　Elsevier　B.V.