The invention provides an insulated down lead clamp and relates to a cable clamp, in particular to an insulated down lead clamp for an optical fiber composite overhead ground wire. The insulated down lead clamp comprises a first connection hardware tool, a composite insulator, a second connection hardware tool, an S-shaped fixing clamp or a rod hoop and a binding wire; the first connection hardware tool is installed at one end of the composite insulator, and the second connection hardware tool is installed at the other end; the S-shaped fixing clamp or the rod hoop is installed at the end of the second connection hardware tool; both ends of the binding wire are spiral; and a bayonet is arranged at the middle part of the binding wire and is fixedly matched with the first connection hardware tool. The composite insulator comprises a core rod and an umbrella skirt; and the core rod is installed in the umbrella skirt. The core rod and the umbrella skirt are both made of insulating materials. The rod hoop comprises an upper hoop and a lower hoop. The insulated down lead clamp is stable to install and is convenient to operate and is used for fixing a connection/down lead cable so as to avoid the friction generated between the cable and a tower during operation and also ensure the insulation between the cable and the rod/tower.