AbstractA series of Ni/MgO‐Al2O3 catalysts with different MgO abundance were prepared by mechanochemical method for CO methanation based‐on slurry‐bed reactor. The prepared catalysts were characterized by X‐ray diffraction (XRD), H2 temperature‐programmed reduction (H2‐TPR), N2 adsorption‐desorption, thermogravimetric analysis (TG‐DTG) and temperature‐programmed hydrogenation (TPH) techniques, and CO methanation performance evaluation was carried out for the samples. Results showed that the catalyst with MgO loading of 2 wt.% (Ni/MgO(2)‐Al2O3) presented smaller Ni grain size of 9.64 nm and larger specific surface area of 329 m2 ⋅ g−1, indicating that a well dispersion of active component on the catalyst. Evaluation results showed that Ni/MgO(2)‐Al2O3 could improve the activity of catalyst for CO methanation. Carbon deposition analysis, from TG‐DTG characterization, found that MgO could significantly inhibit the formation of carbon deposition in the reaction process. The amount of carbon deposition on Ni/MgO(2)‐Al2O3 was the least, only 6.5 %, and the deposited carbon was consisted with the results obtained from TPH analysis. Kinetic analysis showed that the carbon removal reaction mainly occurred at the stage of 250–550 °C. And the activation energy from carbon removal reaction for Ni/MgO(2)‐Al2O3 was lower to 13.12 kJ/mol, demonstrating that the catalyst with MgO as additive is more beneficial to anti‐carbon ability.