The invention provides a double-split wire on-line monitoring device installation fixture and installation method. The installation method is simple and reliable. The installation fixture comprises a coil clamp and a coil; the coil clamp includes an upper clamp and a lower clamp of which the cross sections are semi-circular; one end of the upper clamp is connected with one end of the lower clamp through a rotation shaft; the other end of the upper clamp is connected with the other end of the lower clamp through a connecting component; the lower clamp is connected with a connecting plate of an end portion of a protective sleeve; the lower clamp is connected with a box; a cover is arranged above the box; a circuit board is arranged in the box; the cross section of the protective sleeve is arc-shaped so as to match a wire; and a preformed armor rod is wound on the protective sleeve and the wire. With the double-split wire on-line monitoring device installation fixture and installation method of the invention adopted, a line monitoring device can be fixedly installed on an installation point conveniently and fast, and the line monitoring device can be uniformly stressed after being installed, and no damage will be caused to the wire, and the device will not slide at the direction of the wire at the installation point, and the radial direction of the wire will not rotate, and the fixation of the device can be firm and reliable. The installation fixture can obtain induced electricity from two high-voltage wires.