The utility model discloses an arrester for a direct-current power transmission line. The arrester is characterized by consisting of three arrester body elements and an external serial air clearance. An arrester body is formed by assembling a high-performance direct-current zinc oxide resistance sheet and an explosion-proof epoxy glass cloth insulating cylinder, an external insulator is made from liquid silicon rubber through a one-time integrated injection molding process, the swing amplitude of a lower electrode of the external serial air clearance on a direct-current power transmission conductor is limited by using an installation device, and the arrester has the characteristics of high direct-current aging resistance, good explosion-proof performance, high ultraviolet radiation resistance, high hydrophobicity, stable discharge performance and the like.