Air bag type gland and pneumatic nail gun adopting air bag type gland

The utility model relates to an air bag type gland which comprises a gland body, an air bag, a first piston ring, a second piston ring and an inflator, the air bag is arranged on the gland body, an air hole communicated with the air bag is formed in the position, corresponding to the air bag, of the gland body, an exhaust cavity is formed between the air bag and the gland body, and an exhaust hole is formed in the position, corresponding to the exhaust cavity, of the gland body; the air bag is sleeved on the inflator, an air inlet of the inflator extends out of the cover body, an exhaust port of the inflator extends into the exhaust cavity, the first piston ring is sleeved on the inflator and located above the air bag, and the second piston ring is sleeved on the inflator and located below the air bag. When the air bag expands or shrinks, the first piston ring and the second piston ring rise and fall along the inflator along with the change of the air bag to generate position change, so that the service life