In some cases of the electricity measuring disputes, cheating on transformer measurement is very common, which is adding shunt resistance on the secondary side of the transformer, thereby reducing the load current of the circuit loop in watt-hour meter, and achieve the purpose of reducing the electric energy of measurement. After testing three phase watt-hour measurement performance, voltage transformer measurement performance, current transformer measurement performance, and checking the wiring of transformer in measuring device box, it is found that the cheating method is to artificially solder manganin shunt resistance wire on the back of the terminal blocks. For this case, the effective and feasible way of detection is to compare the values between practical application and the ones on current transformer nameplates.