The invention relates to the technical field of threading devices, in particular to a threading device comprising a machine frame. A rotation drive mechanism driven by a motor is arranged on one side of the machine frame. A guide rail is horizontally arranged on the machine frame. A tailstock is installed on the guide rail in a sliding manner. A cutter rest is arranged on one side of the guide rail. A tailstock handle is installed on the tailstock. The sensing mechanism is fixed to the tailstock. An installation plate is horizontally arranged on the guide rail. The installation plate is provided with a long-strip-shaped limiting opening parallel to the guide rail. When the part is machined, an operator just needs to move the handle to conduct control through two electromagnetic sensors, and then threading can be completed; and in this way, it is not needed to repeatedly press forward and reverse rotation buttons, the machining time is shortened, and the labor intensity of the operator is relieved. Since the positions of the two electromagnetic sensors are fixed to the device, the thread length consistency of the machined part is controlled through the electromagnetic sensor, and the phenomenon that the thread lengths of the workpieces are inconsistent during machining is avoided.