An air cap arrangement and a spray gun. The air cap arrangement comprises an air cap, an air cap ring and a retaining ring. The air cap ring comprises a groove configured to extend on the circumferential inner surface of the air cap ring. The air cap also comprises a groove configured to extend on the circumferential outer surface of the air cap, and the retaining ring is arranged in the groove of the air cap ring and the groove of the air cap to limit the axial movement of the air cap within the air cap ring.