The invention relates to a tool for the live replacement of an over-voltage protection device of a distribution line. The distribution line comprises a conducting wire, a cross arm, an insulator and the over-voltage protection device, wherein the over-voltage protection device and the insulator are arranged in parallel between the conducting wire and the cross arm. The tool comprises an insulating bracket and an insulating operating rod. The insulating bracket comprises a bracket body and a fastening component. The lower end of the bracket body is fixed on the cross arm of the line through the fastening component, and the upper end of the bracket body jacks the conducting wire. The insulating operating rod comprises a chuck, a fastening bolt, an upper cover and a lower cover. One end of the chuck penetrates through the upper cover, and then is fixed. The lower cover is connected with the upper cover through the fastening bolt. After the bracket body jacks the conducting wire, the chuck clamps the over-voltage protection device. Compared with the prior art, the tool has the advantages of ensuring live work, shortening interruption duration, increasing a power supply volume, and the like.