The invention provides a gas producer. The gas producer comprises a feed water collecting box, a membrane wall, a discharge water collecting box and a shell, wherein the feed water collecting box, the membrane wall and the discharge water collecting box are positioned in the shell; the membrane wall comprises multiple water wall tubes with same shapes, the outlet ends of the water wall tubes are positioned at the top end of the gas producer, the tube bodies of all the water wall tubes are arranged side by side along the vertical direction to encircle a cylindrical cavity, the top part of the cavity is opened and necked down to form an access opening, the bottom part of the cavity is necked down to form a gas outlet, and a combustion chamber is formed in the cylindrical cavity; and the bottoms and tops of the feed water collecting box and the membrane wall are communicated with the feed water collecting box and the discharge water collecting box respectively. The membrane wall is provided with multiple water wall tubes with same shapes, the water wall tubes are arranged in a circular array and are arranged side by side along the vertical direction, and two ends of the water wall tubes are bent towards middle sections, so that the membrane wall is simpler in manufacturing process, and the manufacturing cycle is shortened.