Mesoporous nano zirconian was prepared by the self-assembly route using hexadecyltrimethyl ammonium bromide (CTAB) surfactant and employed as support for Nickel catalysts for selective methanation of CO. The CO methanation catalytic performance of the synthesized mesoporous nano zirconia-supported Ni-based catalysts was investigated, and the catalysts were charactered by TG/DSC, BET and XRD techniques. The results showed that, when the Ni loading was under 7.5 wt%, almost all the nickle species were in the form of nanoscale crystallites that finely distributed on the mosoporous nano zirconian surface. These well dispersive nickle species presented unique high activity and selectivity for CO methanation. For all the catalysts studied, the 7.5 wt%Ni/ZrO2 catalyst was the most effective one, which showed a higher than 99% of CO conversion in the CO/CO2 competitive methanation reactions over the temperature interval of 260~280°C, while the CO2 conversion was held at the low level.