The utility model discloses a transformer core earth current detection device of many mutual -inductors, including signal acquisition, signal conversion, signal arrangement and four modules of signal processing, the signal acquisition module is ac current transformer, and ac current transformer gathers the electric current of transformer core or folder, the signal conversion module includes a plurality of transformer coil, and a plurality of transformer coil ranges are different, a plurality of transformer coil simultaneously with ac current transformer's coil coupling, the signal simultaneous transmission after the signal conversion module will be changed gives voltage sample and signal processing module, voltage sample and signal processing module include wave filter, level conversion module and high accuracy adc, and voltage sample and signal processing module carry out filtering and level conversion with the received signal, and high accuracy adc selects the high sample data of precision to transmit for signal processing module 0 and signal processing module 1, signal transmitter carries out spectrum analysis with output module to the received data and obtains fundamental wave amplitude and total current virtual value and output, the device, the precision is high, and linear range is wide, anti -electromagnetic interference can the reinforce.