The utility model relates to a direct-current lightning arrester which comprises an arrester body and a discharge gap group, wherein the discharge gap group is connected with a high-voltage end of the arrester body, the arrester body comprises a plurality of arrester units, every two arrester units are connected by virtue of a flange, a sealing ring and a pressure releasing plate are sequentially arranged at the top and the bottom of each arrester unit, the flanges are arranged at tail ends of the arrester units and used for closing the sealing rings and the pressure releasing plates therein, each arrester unit sequentially comprises an outer sleeve, an epoxy pipe and a resistor column from outside to inside, the resistor column is formed by serially connecting a plurality of resistors, the height of the arrester body is 7.5m-9m, preferably 8.2m, the discharge gap group comprises an upper-part discharge electrode and a lower-part discharge electrode, and an air gap distance between the upper-part discharge electrode and the lower-part discharge electrode is 2.3m-2.6m. The direct-current lightning arrester is simple in structure, small in volume and convenient to install, large in regulating range of an air gap, and reasonable in technical parameters, and has a good application prospect.