The invention relates to an airbag retarder and a retarding method employing the same. An exhaust system of a common retarder is open to the outside; the common retarder mounted on a field steel rail throughout the year often encounters severe weather such as rain, water may enters an exhaust pipe and flows into the retarder, and the inside of the retarder rusts; in case of heavy snow, the exhaust pipe may be blocked by the snow; at low temperature, the exhaust pipe is frozen and fail to normally exhausts. The airbag retarder comprises a piston rod (5) in a sliding cylinder (1); a speed valve plate (13) is connected to the piston rod (5); the sliding cylinder and the piston rod form a high-pressure upper cavity; the left side of a housing is provided with an exhaust line connected with an airbag (16); the housing is provided with a return line connected to the airbag; a lower cavity of the sliding cylinder is connected with a hydraulic oil pump; a return valve is mounted on a hydraulic oil pipeline; the sliding cylinder is connected with a helium pump. The airbag retarder is applicable to retarding.