Pneumatic vibrator, using the air compressor discharge of high pressure gas through the air pipe into the product inlet, when the gas pushes the piston up, the gas in the piston upper chamber is squeezed, the squeezed gas is discharged through the exhaust hole. When the piston goes up to the end, the gas automatically switches the ventilation direction through the groove and the air channel, so that the gas enters the upper gas chamber of the piston. The high pressure gas pushes the piston down to the end of the first cycle, the second cycle begins, and the continuous reciprocal cycle makes the vibrator produce flat and shaking, thus generating vibration force.