Abstract: When the transformer is put into operation again, in order to quickly establish the magnetic field, there will often be an exciting inrush current, and the presence of the transformer's remanence will further increase the amplitude of the excitation inrush current, making the protection of the transformer misoperate. After the electrical test of the transformer, due to the DC current applied in the electrical test, the remanence in the transformer core will further increase, causing hidden dangers to the normal operation of the transformer. Therefore, the reduction or elimination of remanence before the transformer is put into operation is one of the factors to ensure the normal operation of the transformer. This paper mainly studies a degaussing instrument with transformer degaussing function and low voltage AC remanence verification function. The transformer remanence is detected and reduced, so as to improve the transformer degaussing judgment ability and efficiency.