A spray gun head comprises a flow distribution mechanism having an annular shield member disposed around a nozzle thereof and a plurality of apertures around the flow distribution mechanism; a cap comprising a central orifice and two pairs of holes at two opposite sides thereof, such that a mouth of the nozzle is adapted to dispose in the orifice when the cap is put on the flow distribution mechanism; and a ring threadedly secured onto the flow distribution mechanism for closing a pass between the rear of the cap and the flow distribution mechanism. By utilizing this spray gun head, both air flow and air pressure leaving the flow distribution mechanism are made uniform for obtaining an excellent spray on balance and atomization.