The utility model discloses a lightning arrester with a gap. The upper end portion of a core rod is provided with a first fitting, the lower end portion of the core rod is provided with a second fitting, and the body of the core rod is coated with a sheath; a lightning arrester assembly is of a hollow cylindrical structure, and is sleeved on the upper end of the core rod, and one end of the lightning arrester assembly is connected with the first fitting; one end of an insulating cylinder is sleeved on the lightning arrester assembly, the other end of the insulating cylinder extends to the lower end of the core rod, and a hollow cylindrical gap is defined by the insulating cylinder and the core rod; a discharge electrode is arranged in the gap, the discharge electrode comprises an upper electrode and a lower electrode, the upper electrode is arranged at one end, of the lightning arrester assembly, being close to the second fitting, and the lower electrode is arranged between the second fitting and the insulating cylinder; and a sheath umbrella skirt is arranged on the insulating cylinder. By arranging the discharge electrode on the lightning arrester to form a gap electrode, the lightning arrester assembly is prevented from bearing voltages for a long time, the chargeability of the lightning arrester assembly is reduced, the service life of the lightning arrester assembly is prolonged, at the same time, due to the fact that the gap electrode is arranged in the insulating cylinder, the lightning arrester with the gap is concise and tidy in appearance and is convenient to transport and install.