Abstract: The method for catalytic methanation of synthesis gas includes the following steps: 1) feeding the synthesis gas into the bottom of a reactor of an upward concurrent flow transporting bed so as to adequately mix and preheat with methanation catalyst entering the bottom of the reactor until the activation temperature of the catalyst is reached and then the methanation reaction begins; and 2) after the methanation reaction, immediately passing the product gas and the catalyst grains outputted from the transporting bed into a gas-solid separator to perform a rapid separation so as to obtain the product gas.