Powder spray gun

The invention discloses a powder spray gun. The powder spray gun comprises an inner pipe, an outer pipe, an outer nozzle and an inner nozzle. A first medium passageway is formed in a pipe cavity of the inner pipe, the inner pipe is sleeved with the outer pipe, a second medium passageway is formed between the outer wall face of the inner pipe and the inner wall face of the outer pipe, the outer nozzle is connected to the outlet end of the outer pipe, the inner wall face of the outer nozzle is conical, the internal diameter of the outer nozzle is gradually reduced in the direction from an inletof the outer nozzle to an outlet of the outer nozzle, the inner nozzle is connected to the outlet end of the inner pipe, the inner nozzle is a hollow cone, the internal diameter and the external diameter of the inner nozzle are both gradually reduced in the direction from an inlet of the inner nozzle to an outlet of the inner nozzle, the inner nozzle is sleeved with the outer nozzle, a third medium passageway is formed be