The invention discloses a pneumatic bending machine. The pneumatic bending machine comprises a rack, a locating device, a pneumatic prepressing device, a pneumatic bending device and an electronic control device, wherein the locating device is arranged on the rack and is used for bearing a product to be bent, the pneumatic prepressing device is used for tightly pressing the product to be bent on the locating device through vertical movement, the pneumatic bending device is used for bending the product to be bent through stretching and contraction movement, the electronic control device is electrically connected with the pneumatic prepressing device and the pneumatic bending device, and is used for having control over movement of the pneumatic prepressing device and movement of the pneumatic bending device, the pneumatic bending device comprises bending plunger chips, a plunger chip base, elastic component locating pins, elastic components, stroke control pins and bending air cylinders fixedly connected with the stroke control pins, guide grooves are formed in the plunger chip base, one end of each bending plunger chip penetrates through the corresponding guide groove to be opposite to the product to be bent, the other end of each bending plunger chip is close to the corresponding stroke control pin, the elastic component locating pins are fixed to the plunger chip base, each elastic component locating pin is sleeved with one end of the corresponding elastic component, and the other end of each elastic component abuts against the other end of the corresponding bending plunger chip.