The invention discloses a protective door device of a cable former in the field of safety devices of cable formers, comprising a protective door arranged on a cable former body; a protective lock is arranged between the protective door and the cable former body, and whether the protective lock is unlocked or not is controlled by a control circuit; the control circuit comprises a signal acquisition circuit, a comparison and signal sending circuit and a protective lock executing circuit, wherein the signal acquisition circuit is used for acquiring a rotating signal for showing whether rotating equipment in the cable former rotates or not and transmitting the rotating signal to the comparison and signal sending circuit; and the comparison and signal sending circuit is used for judging and sending out a signal for showing whether the lock can be unlocked or not to the protective lock executing circuit. The protective lock can be unlocked after all rotating equipment inside the cable former stops, then the protective door can be opened for inspection and maintenance so that the inspection and the maintenance are safer; when the cable former is normally started up, the protective lock is in a locked state; and after the inspection and the maintenance, the equipment can be restarted up when the protective lock is reset to a safe state.