A nozzle of a spray gun includes an air cap, a board, a cover and a nozzle. The air cap has a central path. The central path has a first inner periphery and a second inner periphery which is larger than the first inner periphery. Two guide faces each are a tapered face which is connected between the first and second inner peripheries of the central path of the air cap. The two guide faces are located symmetrically relative to the central path. Two air holes are respectively defined between the two guide faces and the nozzle. The air flow from the guide faces interests the air flow form the air holes to increase the range of the air flow to guide the paint in the paint path to be ejected from the nozzle.