The invention relates to the technical field of transformers, and discloses a transformer abnormal magnetic flux leakage monitoring system. The transformer abnormal magnetic flux leakage monitoring system comprises a transformer and a recording device. The transformer comprises a fuel tank and a magnetic shield. The magnetic shield is connected on an inner wall of the fuel tank, and an outer surface of the magnetic shield is wound with a coil. Both ends of the coil pass through side walls of the fuel tank and are connected to the recording device. The coil is wound on the magnetic shield, andthe two ends of the coil pass through the side walls of the fuel tank and are connected to the recording device; the magnetic flux leakage can be converted into a voltage signal through the coil, thevoltage signal on the coil is acquired by the recording device, and the waveform of the voltage signal is displayed to reflect the state of magnetic flux leakage through the waveform of the voltage signal, thereby realizing the monitoring of the magnetic flux leakage inside the transformer to ensure that the abnormal magnetic leakage of the transformer can be found in time, and then the normal operation of the transformer can be ensured.