The actuator and adjustment mechanism of the pneumatic actuator are a unified whole. The actuators include diaphragm type, piston type, fork type and rack and pinion type. The piston type has a long stroke and is suitable for occasions requiring larger thrust;while the diaphragm type has a smaller stroke and can only directly drive the valve stem. The fork-type pneumatic actuator has the characteristics of large torque, small space, and the torque curve is more in line with the torque curve of the valve, but it is not very beautiful;it is often used on high-torque valves. Rack-and-pinion pneumatic actuators have the advantages of simple structure, smooth and reliable action, and safety and explosion-proof. They are widely used in power plants, chemical industries, oil refining and other production processes with high safety requirements.