According to the principle of differential method, the main insulation structure of the capacitor voltage current transformer, the network equivalent model, through two similar operating devices are measured values, which are related to three parameters: the two phase, the same phase, the voltage measurement of the terminal screen of the same phase, the type of capacitive voltage current transformer, and the voltage measurement between the devices, and the end of the two devices, the voltage measurements, judging whether there is fault equipment, judging whether there is fault equipment, judging whether there is fault equipment, judging whether or not, judging whether there is fault equipment, judging from the two different periods, judging whether there is fault equipment, judging from the voltage measurement, and the use of differential mode, the method of measuring the capacitance type high voltage transformer equipment. Easy to use, and so on, is to carry out the operation of capacitive type substation equipment operation state detection work and a new method.