The invention discloses a quantity regulating device for an airflow racking machine and relates to the field of pharmaceutical machinery. The quantity regulating device comprises a circular disc and sliding blocks, wherein the middle of the circular disc is provided with a connecting hole; the sliding blocks are arranged on the circular disc and are connected with charging pistons; a plurality of slideways uniformly distributed on the circular disc at the periphery of the connecting hole; each slideway is internally provided with one sliding block and an adjusting screw rod which is matched with the sliding block and used for driving the sliding block to slide along the slideway; the sliding blocks are provided with through threaded holes in the sliding direction of the slideways; threads at the middle sections of the adjusting screw rods are matched with the threaded holes in the sliding blocks; two ends of each adjusting screw rod are provided with polish rods which are respectively connected to two ends of the corresponding slideway in a sleeving manner; the parts, which correspond to the polish rods of the adjusting screw rods, of the circular disc are provided with jack screws for fastening the adjusting screw rods. The quantity regulating device can be used for respectively controlling each piston, and respectively adjusting the charging quantity of each piston so as to achieve more accurate charging quantity.