The invention relates to an external thread of a sealing pipeline, which can realize sealing without utilizing filler, wherein an effective thread is a thread of a conical tube; the middle of the total length of the effective thread is provided with at least two complete variable convex threads; the intermediate diameter of the variable convex thread is more than the intermediate diameter of a corresponding reference standard taper thread by preset interference fit quantity; and the tooth side of the variable convex thread is outer convex cambered surface. The invention also relates to a method and a device for manufacturing the external thread of the sealing pipeline and a thread pair pipe fitting of a guide-type interference fit pipe.