Abstract: An improved spray paint gun, comprises a regulating port in the intersection between the inlet channel, main spray channel and side spray channel. The regulating port is provided with a regulating ring and the regulating is being provided with first, second and third apertures in the position corresponding to each of the inlet channel, the main opening and the side opening respectively. A regulating element is screwed onto the regulating port by a connecting element disposed at the regulating element. The connecting element is provided with a movable regulating rod which may insert into the regulating port. When the regulating rod moves downward to close the side spray channel completely, the thickness of the regulating port can be increased by the provision of the regulating ring to regulate the air stream pressure flows therethrough. Accordingly, the air stream pressure inside the main spray channel can meet the requirements of HVLP (high volume low pressure).