The invention relates to an insulating protective cover of an isolating switch. The insulating protective cover includes a case structure formed by bottom parts of two half housings which are hinged and correspondingly buckled. Each half housing has a wide middle part and two narrow end parts. A middle part of the case structure constitutes a cavity for receiving the isolating switch and insulators. Two ends of the case structure are openly arranged and respectively form a channel at two end parts for passage of a cable. Bottom walls of the two half housings are separately and rotatably provided with handles each of which is fixedly provided with a locking mechanism thereon for buckling and locking the case structure. The bottom wall of each half housing is vertically and fixedly provided with a threaded rod. Each handle rotatably sleeves one threaded rod. Each locking mechanism includes a pressure plate which is vertically and fixedly connected to a top end part of one handle and can press against the bottom wall of the other half housing. Each pressure plate and the bottom wall of the other half housing are provided with a positioning mechanism therein. The positioning mechanism can lock rotation angle of the pressure plate. According to the invention, the insulating protective cover has the advantages of simple structure, easy and rapid operation, stable structure, and safety and reliability.