In order to solve the problem that the structures of a
nozzle and a
throat section need to be redesigned and manufactured when the
area ratio of an existing ejector is changed, the invention provides a gas ejector which comprises a suction chamber, a
diffusion outer cylinder and an exhaust
tail pipe which are sequentially communicated and coaxial, wherein the
diffusion outer cylinder comprises a mixing part, a contraction part, a
throat part and an expansion part; and the suction chamber is fixedly provided with an annular spray
pipe, a
diffusion cone is fixedly arranged in the diffusion outer cylinder and comprises a conical cone section I, a circular truncated cone-shaped cone section II and a circular truncated cone-shaped cone section III, the conical section I, the conical section II and the conical section III are sequentially and coaxially connected, the diffusion cone is coaxial with the diffusion outer cylinder, the bottom of the conical section I is connected with the upper bottom of the conical section II, the bottom of the conical section II is connected with the lower bottom of the conical section III, the lower bottom of the conical section II is connected with the lower bottom of the third conical section, the conical section I is located in the contraction part, the conical section II is located in the
throat part, the conical section III is located in the expansion part, and the outer molded surface of the conical section II is parallel to the inner wall of the throat part. The gas ejector is compact in structure, facilitates the size with higher throat sections, simple in structure, easy to
machine and manufacture and convenient to
mount.