The invention discloses a spiral groove tap machining method, and relates to a tap machining method. The problem that at present, no spiral groove tap machining method exists is solved. The method comprises the steps that a rough bar is sawn on a sawing machine; an outer circle is subjected to rough turning on a horizontal lathe; a tap and a tail handle are subjected to butt welding to form a whole; the tap part is subjected to turning on the horizontal lathe, wherein the tap is subjected to turning to achieve the outer diameter being phi 45, the tail handle is subjected to turning to achievethe outer diameter being phi 31.5, the head of the tap is cut to obtain a taper angle, a tap thread is subjected to turning, and turning is conducted to achieve the pitch diameter being phi 43.051 andthe pitch diameter volume being 0.6-0.7 mm; a groove is machined through a horizontal milling machine, a tail handle 25*25 square tail is machined on the horizontal milling machine; heat treatment isconducted; center holes formed in the two ends are ground; the tap outer circle is ground on an external grinder; grinding is conducted on a numerical control grinder accurately to achieve the rake angle being 10 degrees and the right-hand helical angle being 35 degrees; a cone and a relief angle thereof are ground and cut on a relieving grinder; a 60-degree tooth profile and a relief angle thereof are ground accurately on a thread grinder, and the pitch diameter back tape is 0.06/100. The method is used for machining a spiral groove tap.