Abstract: The experiment was conducted based on an industrial nickel-based catalyst. The effects of operating temperature, feed ratio, and operating pressure on the methanation and the factors for the catalyst deactivation were investigated. The results indicate that the formation rate of CH₄ increases with operating temperature, pressure, and CO concentration. But the concentration of CO can not be excessive, because the activity of catalyst will gradually decrease if H₂/CO≤3. The carbon deposit is found on the surface of deactivated catalyst by X-Ray Diffraction(XRD) and Energy Dispersive Spectrometer (EDS) analyses. It can be concluded that the deactivation of catalyst may be related to the surface carbon deposition. The BET surface area analysis shows that the rate of carbon deposition is related to the reaction temperature, and the higher the temperature, the faster the coking.