NOVELTY - Synthesizing natural gas comprises adding nickel(II) oxide (NiO) precursor, reducing the NiO precursor in a reducing atmosphere of nitrogen and hydrogen, then adding a catalyst into a storage tank, mixing the catalyst with a nickel (Ni) catalyst, carrying out a methanation reaction on a raw material gas under the action of the catalyst, feeding a product gas into a separator I, discharging a liquid-phase component I and a gas phase I, leading a part of liquid phase containing the catalyst to a separator II, and mixing the gas phase II with the gas phase I to obtain a natural gas product.    USE - The process is useful for synthesizing natural gas through methanation (claimed).    ADVANTAGE - The process is capable of avoiding a problem of self-ignition of the reducing catalyst.    DETAILED DESCRIPTION - Synthesizing natural gas comprises adding nickel(II) oxide (NiO) precursor into a fixed-bed reducing apparatus at a reducing temperature, reducing the NiO precursor for 1-10 hours in a reducing atmosphere of nitrogen and hydrogen, then adding a catalyst into a fresh catalyst storage tank through a spiral conveyer, where a liquid phase dispersant storage tank is connected to the fresh catalyst storage tank, mixing the catalyst with a nickel (Ni) catalyst, uniformly stirring a catalyst suspension in the fresh catalyst storage tank in a slurry bubble column methanation reactor through a circulating pump, carrying out methanation reaction on a raw material gas under the action of the catalyst, feeding a product gas into a separator I, discharging a liquid-phase component I through a bottom of the separator I and discharging a gas phase I through a top of the separator I, leading a part of liquid phase containing the catalyst to a separator II from a middle part of the reactor, discharging a gas phase II through a top of the separator II and mixing the gas phase II with the gas phase I to obtain a natural gas product, discharging the liquid-phase component II containing the catalyst through the bottom of the separator II and mixing with the liquid-phase component I, discharging one part of the mixed liquid-phase component, and feeding the remained part that is cooled previously together with a fresh catalyst turbid liquid, into the slurry bed methanation reactor through the circulating pump to join in the methanation reaction.