The invention provides a manual and automatic 
clutch structure of a 
pneumatic actuator. The manual and automatic 
clutch structure comprises a 
pneumatic actuator body, a speed 
reducer mechanism and a manual and automatic 
clutch mechanism arranged between the 
pneumatic actuator body and the speed 
reducer mechanism, wherein the pneumatic 
actuator body comprises an output shaft; the speed 
reducer mechanism comprises an input shaft and a box cover; and the manual and automatic clutch mechanism comprises a sliding sleeve and a toggling unit, wherein the toggling unit comprises a rotating shaft and a locating pin, the rotating shaft is arranged in a through hole of the box cover, the locating pin is arranged at the end, facing to the input shaft, of the rotating shaft, the 
central line of the locating pin is deviated from the 
central line of the rotating shaft, and the top of the locating pin is arranged in a locating slot formed in the outer surface of the sliding sleeve. According to the manual and automatic clutch structure of the pneumatic 
actuator, provided by the invention, the arrangement of the sliding sleeve decides the connection and disconnection of the pneumatic 
actuator body and the speed reducer mechanism, and furthermore manual and automatic working states are kept between the pneumatic actuator body and the speed reducer mechanism; and due to the adoption of the design, operation difficulty caused by overlarge torque cannot be generated when manual operation is adopted, so that the physical power is saved.