Abstract: A nozzle for paint spray guns, including a tubular nozzle body having a conical nozzle tip at one end and an outer thread at an opposite end, a first collar tightly mounted around the tubular nozzle body and having a plurality of axial through holes; and, a second collar tightly mounted around the tubular nozzle body between the first collar and the outer thread of the tubular nozzle body and having a plurality of axial through holes which are not in longitudinal alignment with the through holes of the first collar and through which compressed currents of air are driven toward the through holes of the first collar, after a mixing process at the annular space defined between the first collar and the second collar, to mix with the output spray of paint into a good atomization of paint.