The insulation detector is used in disinfection supply center, operating room, endoscope room and other departments to conduct on-site internal and external insulation or on-off detection of active medical devices. This series of insulation detector is specially designed for the fault detection of medical devices with power supply. It is convenient to use, simple to operate, accurate to locate the fault point, and can quickly detect the damage on the insulation layer of the device that can not be seen by the naked eye. It not only protects the safety of patients and medical personnel in the whole process, but also enables the operation to be truly foolproof.