The invention relates to the technical field of electrical engineering, and discloses a lightning arrester. The lightning arrester comprises an insulating hollow rod, multiple resistor discs and metalcushion blocks, air outlets are formed in the upper end and the lower end of the insulating hollow rod respectively, the resistor discs and the metal cushion blocks are arranged in the circumferential direction of the insulating hollow rod, the multiple resistor discs are arranged in the axial direction of the insulating hollow rod, the metal cushion blocks are arranged between every two adjacentresistor discs, and heat emission holes are formed in the surface where the insulating hollow rod makes contact with the resistor discs. According to the lightning arrester, a heat dissipation channel of the resistor discs is formed through a hollow insulating tube and the metal cushion blocks, the heat dissipation speed of the lightning arrester in the high temperature condition is increased, and then the capacity of the lightning arrester for dealing with icing flashover and lightning tripping fault is improved, and the safety and reliability of the device are greatly improved.