Resistance is the most important indicator for the normal use of wires and cables. Therefore, it is important to detect abnormal insulation resistance. Insulation resistance reflects the actual ability of wires and cables to withstand voltage and current, and also to some extent reflects the loss ability of insulation materials in working conditions, which can provide a basis for other inspections. When measuring resistance, separate measurements should be made on the constituent materials of different resistances. The main method used in insulation resistance measurement is the high resistance recording method, which means that the voltage is constant during the process of passing through the wire resistance, and then the maximum resistance data is detected. The normal insulation resistance value of the wire and cable is calculated based on the data for testing.