The invention provides an insulating sheath for a connection point of an overhead insulated conductor, and the insulating sheath employs a thermal contraction structure. The insulating sheath comprises an insulating protection layer which is made of an elastic insulating material, and wraps a conductor connection point. The insulating protection layer also comprises a thermochromic material whichchanges colors according to the temperature of the conductor connection point. The insulating sheath employs the thermal contraction structure, and is simple and easy in installation. The joint does not need to be sealed, and the insulating sheath can firmly wrap the insulated conductor. The insulating sheath is good in sealing performance, is good in age resistance, is long in service life, and wide in application range. Through the adding of the thermochromic material, the insulating sheath can reflect the temperature of the connection point of the overhead insulated conductor in real time,achieves the safety early warning effect, reduces the workload of line detection of a maintainer, and improves the work efficiency.