The invention provides an universal joint for internal threads and external threads, a pipeline, a method and a closestool. The universal joint comprises a nut and an external thread joint; a part ofthe inner side of the nut is an external thread coupling area, and a part of the inner side of the nut is an external thread decoupling area; the external thread joint is arranged in the nut in a sleeved mode, a part of the outer side of the external thread joint is an internal thread coupling area, and a part of the outer side of the external thread joint is an internal thread decoupling area, the external thread joint can rotate in the nut and move in the axial direction. The universal joint for the internal threads and the external threads can be compatible with and matched with the internal threads and the external threads, and the limitation that a pipe can only be matched with one kind of the internal threads or the external threads is broken; and sealing nodes are reduced, the sizeof the joint is relatively small, and the connecting effect is attractive.