Abstract: Ni-Ce/Al₂O₃ catalysts with different Ce contents were prepared by wet impregnation method using γ-Al₂O₃ as support, and their catalytic performance of CO methanation in slurry-bed reactor were evaluated. The catalysts were characterized with XRD, BET, H₂-TPR, CO-TPD, and the relationship between the microstructural properties of catalysts and CO methanation in slurry-bed reactor was investigated. The results indicated that the addition of Ce into Ni/Al₂O₃ catalyst strengthened the interaction between Ni species and the support and enhanced the CO adsorption. With the increase of Ce content, the dispersion of Ni species on support was improved, the particle size of nickel decreased, the specific surface area and the relative content of β-NiO with stronger interaction with support increased firstly and then decreased. The catalytic performance of CO methanation in slurry-bed changed regularly with the increase of Ce content, the conversion of CO and the space-time yield (STY) of CH₄ were all increased firstly and then decreased slightly. When the content of Ce reached 4%, the catalyst exhibited the best catalytic performance.