Machining method of high-precision and difficult-to-position three-way pipe

The invention discloses a machining method of a high-precision and difficult-to-position three-way pipe. The machining method of the high-precision and difficult-to-position three-way pipe comprises the following steps: (1) material receiving: receiving a blank; (2) first milling: positioning according to a center line, finding a reference, and milling processing references of cylindrical surface shapes by using a three-axis milling machine, namely a left lug and a right lug which are symmetrical; (3) first turning: turning conical surfaces of the two symmetrical lugs by using a two-axis lathe according to the milling references in the step (2); (4) secondary milling: positioning according to a center line, finding a reference, and milling a processing reference of a cylindrical surface shape by using the three-axis milling machine, namely a middle lug; (5) secondary turning: turning the conical surface of the middle lug by using the two-axis lathe according to the milling reference in the step (4); and (6) t