Selective　methanation　of　CO　(SMET)　is　promising　for　deep　removal　of　low-concentration　CO　in　excess　H2.　However,　the　development　of　suitable　catalysts　applied　in　practical　conditions　remains　a　great　challenge.　Here　we　report　a　general　strategy　to　develop　highly　efficient　SMET　catalysts　by　using　hydrogenated　TiO2　(H-TiO2)　as　support.　The　H-TiO2　supported　Ru　catalysts　can　remove　CO　to　below　10　ppm　with　greater　than　50　%　selectivity　in　a　wide　temperature　range　of　200-265　degrees　C,　with　a　good　long-term　stability.　Detailed　characterizations　including　operando　spectroscopy　and　in-situ　XPS　combined　with　DFT　calculation　revealed　that　the　lowered　Ru　valance　on　H-TiO2　strengthens　CO　adsorption　on　both　metal　surface　and　metal-support　interface　which　improved　CO　activation　and　inhibited　CO2　hydrogenation,　respectively,　leading　to　enhancement　of　both　activity　and　selectivity.