The invention relates to an electricity stealing detector and a use method thereof, and belongs to the technical field of electricity stealing detection. The technical scheme is that an inverted U-shaped Rogowski coil (1) is hung on the incoming 10kV line outside the power consumer, the current on the 10kV line is measured by the measuring end and wirelessly transmitted to the data receiving end,and the data receiving end compares the measured current on the 10kV line with the secondary current of the power supply enterprise power consumption system background; and if the current mismatches,the electricity stealing behavior of the power consumer can be determined. The beneficial effects of the electricity stealing detector are that the current on the consumer 10kV line is measured to becompared with the secondary current of the power supply enterprise power consumption system background to determine the electricity stealing behavior of the consumer, and then comprehensive check andother measures are taken in a targeted way so that the electricity stealing evidence can be locked and detailed check can be avoided. The electricity stealing detector is convenient to use and accurate in detection for various electricity stealing modes.