The invention discloses a gas inlet device for a novel microporous aerator. The novel microporous aerator comprises an elastic aeration membrane with micropores and a supporting seat. The aeration membrane is supported by the supporting seat, the supporting seat comprises a hollow ring base, a cross support arm and a central gas inlet pipe, the cross support arm is connected with the bottom surface of the hollow ring base, the central gas inlet pipe is connected with the tail end of the cross support arm, the bottom of the central gas inlet pipe is sealed, a ring surface of the hollow ring base is a protruded arc-shaped ring surface, the cross support arm comprises four oblique support arms, one end of each support arm is connected with the bottom surface of the ring base, gas distribution channels are arranged in at least one pair of symmetric support arms and are communicated with radial gas inlet grooves in the surface of the ring base, each radial gas inlet groove is formed in a corresponding boss of the surface of the ring base and is perforated through two ends of the boss, oblique downward slope surfaces are arranged at two ends of each boss, the supported aeration membrane is an annular arc-shaped surface and is provided with thickening convex ribs which correspond to the radial gas distribution grooves and are matched with the radial gas distribution grooves, the bottoms of the thickening convex ribs are embedded in the radial gas inlet grooves, gas distribution openings are formed in slope surface perforation openings in two ends of each radial gas inlet groove, and the supported aeration membrane is divided into a plurality of aeration zones by the thickening convex ribs and the radial gas inlet grooves.