Disclosed in the invention is an insulated-wire linear-rod lightning arrestor comprising a direct-lightning arrestor, side-lightning arrestors, a cross arm, and a mounting rod. The direct-lightning arrestor is installed on the top of the mounting rod; and the side-lightning arrestors are installed at the two ends of the cross arm. The cross arm and the mounting rod are installed on the top of a telegraph pole; and the cross arm is perpendicular to the telegraph pole and the mounting rod and the telegraph pole are parallel to each other. A lightning-protection angle A formed by the direct-lightning arrestor and the outermost insulated wire is less than 25 degrees; and a lightning-protection angle B formed by the side-lightning arrestorand the outermost insulated wire is less than 25 degrees. The side-lightning arrestors are tilted towards the outer side of the telegraph pole; and a tilting angle C of the side-lightning arrestor is larger than 8 degrees and is less than 20 degrees. The cross arm and the mounting rod are connected with a ground wire; and the lower end of the ground wire is connected with a ground stud by a ground bandlet. According to the invention, the lightning arrestor has a simple and durable structure. With the direct-lightning arrestor and the side-lightning arrestors, prevention of direct lightning and side lightning is combined, so that the line protection capability is enhanced.