The pneumatic actuator of the GIQ-B series pneumatic high vacuum butterfly valve is powered by compressed air and changes the direction of the air circuit through an electromagnetic directional valve, pushing the mechanical transmission of the piston rack and gear, and outputting torque through angular stroke to drive the butterfly valve for opening and closing motion. In order to achieve the purpose of connecting or cutting off the airflow in the vacuum pipeline, it is a new type of pneumatic butterfly valve controlled by pneumatic actuators. It is divided into double acting and single acting (spring return) cylinders, and can be equipped with feedback signal devices and electrical valve positioners. The applicable working medium is air and non corrosive gases.