The invention discloses an improved welding gun regulating valve assembly which comprises a regulating valve and a reducing valve, wherein the regulating valve is fixed on an air valve nut through a regulating handle and is also provided with a locknut connected with a regulating nut; the air valve nut is matched in the regulating nut in a sliding manner and connected with a regulating screw rod,the shape of the regulating screw rod and the shape of the regulating nut are matched in a matching part of the regulating screw rod and the regulating nut, and an O-shaped seal ring is arranged on the end face of the regulating valve; and the small end of the regulating screw rod is arranged on a spring of a spring seat, the spring seat is arranged in a middle through hole of a round nut, the round nut and the regulating nut are connected to the inner wall of a valve body, and the round nut presses a gasket and a sealing gasket. All assemblies of the regulating valve are mutually matched andrestricted, the regulating handle is rotated to push the regulating screw rod to move along a set track, and the regulating handle does not change the axial position of the valve body. When two limiting positions of a gas channel are opened and closed, the gas channel is in rigid contact with the regulating screw rod, an operator safely uses the improved welding gun regulating valve assembly, thevalve cannot be damaged even if large force is applied, the O-shaped sealing ring has a damping buffer function when the regulating handle is rotated, thus the improved welding gun regulating valve assembly has good handfeel and is comfortable in use.