Abstract: For problems of long adjustment time and low adjustment precision of traditional air regulator, an automatic passageway air regulator with full section was developed, and accurate measurement and control principle of air section of the air regulator was introduced. The air regulator is composed of a supporting frame, a pneumatic motor, a push rod, a door body, a guide plate and a rotary encoder. Under the pressure of compressed air, the pneumatic motor rotates at high speed and drives the push rod to push the door body and the guide plate to move, so as to realize rapid adjustment of air regulator area. The rotary encoder records revolutions of the pneumatic motor. The field application shows that the maximum error of air area adjustment is 0.385%, and area adjustment time is less than 60 s.