The invention discloses a pneumatic clamping jaw. The pneumatic clamping jaw comprises a slide rail, an electric hoist, a rotary rod, a steel wire, a hook, a first guide telescopic rod, a second guidetelescopic rod, a first supporting square rod, a second supporting square rod, a first driver, a second driver, a motor, a rotary shaft, a rotary plate, a first supporting rod body, a second supporting rod body and an air cylinder. A clamping seat body is installed at the lower end of the air cylinder, a first clamping jaw body is movably installed in the clamping seat body, a second clamping jawbody is movably installed in the clamping seat body, and an air cylinder rod of the air cylinder drives the first clamping jaw body and the second clamping jaw body to move; a first L-shaped clampingblock and a second L-shaped clamping block are fixedly installed on the clamping wall face of the first clamping jaw body through bolts, and a third L-shaped clamping block and a fourth L-shaped clamping block are fixedly installed on the clamping wall face of the second clamping jaw body through bolts; and a driver is fixedly installed at the lower end of the clamping seat body, and an arc-shaped clamping block is installed at the bottom end of the driver.