The invention discloses a self-arc-quenching parallel gap device, belongs to the technical field of prevention of lightning failures of power transmission lines, and aims to provide a self-arc-quenching parallel gap device of a lightning arrester serial gap spherical electrode, which is additionally arranged on one side of an insulator of the power transmission line so as to reliably dredge lightning current and prevent a permanent fault caused by erosion of an overcurrent point of the power transmission line. According to the technical scheme, the bottom end of a lightning arrester is fixedly connected with the grounding side of the insulator through a bracket; a lower electrode of the gap spherical electrode is fixedly mounted at the top end of the lightning arrester; an upper electrode of the gap spherical electrode is connected with a conductor in a lead wire insulator through a drainage tube; the drainage tube is formed in the way that at least one metal puncture is arranged in a metal tube; the upper electrode and the lower electrode of the gap spherical electrode are perpendicularly aligned; the lower end of the lightning arrester is fixedly connected with one end of a grounding wire, and the other end of the grounding wire is reliably grounded. The self-arc-quenching parallel gap device is mounted on a lead wire to dredge the lightning current.