A pneumatic mechanism includes: a casing having a main body and a base seat; a drive mechanism disposed in the main body; a first air bypass disposed in the main body, a rear end of the first air bypass communicating with the drive mechanism; a second air bypass having a rear end positioned on the base seat; at least one airflow passage disposed on the base seat, one end of which communicating with the second air bypass; at least one sucker disposed on the base seat; and at least one air-sucking passage disposed between the base seat and the sucker. One end of the air-sucking passage communicates with the air chamber of the sucker, the other end communicates with the airflow passage. The pneumatic mechanism is powered by one single power source to operate and produce sucking force.