The invention relates to an insulating protective box for live working and an installation device and an installation method of the insulating protective box. According to the installation method, firstly, a grip arm of an installation device is pressed and a clamp body clamps the insulating protective box; a hand-held lever of the installation device is held in a hand and the insulating protective box sleeves a connection point of equipment; the angle of the clamp body on the installation device is adjusted, so that the angle of the clamp body is located at the position at which snap fasteners on the insulating protective box are easy to clamp; and the hand-held lever of the installation device is held in the hand, the clamp body is aligned with the snap fasteners on the insulating protective box and various snap fasteners are sequentially clamped. A worker can utilize the installation device provided by the invention and achieve live installation and fixation of the insulating protective box of the equipment by an insulating rod method through a common high-altitude operation platform, high-altitude operation car or stool rod; the problem that the insulating protective box cannot be reached by an insulating glove method is solved; the direction of the clamp body of the installation device is adjustable; and the protective box can be simply and conveniently installed at different azimuths.