In order to obtain the characteristics of CO methanation process, the numerical simulations are carried out in fluidized bed reactor. The model is validated by comparing the simulation results of gas composition with experimental data. The influences of operational parameters on H2 conversation and CH4 yield are evaluated. The CO conversion and selectivity of CH4 increase with raising pressure, but decrease with the growing of temperature. The increase of catalyst inventory leads to difficulty in removal of reaction heat and reducing the production of CH4. The superficial gas velocity influences the production of methane slightly, but the reaction rates. Moreover, the CH4 production and CO conversion decrease with the decrease of ratio of H2/CO of feed composition. Meanwhile, the performance of water-gas shift reaction on CH4 yield is also analyzed. The addition of water into feed composition benefits the production of methane and the CO conversion.