Casing electromagnetic instrument calibration system and calibration method

The invention belongs to the technical field of oil and gas field engineering logging, and particularly relates to a through-casing electromagnetic instrument calibration system and method. The through-casing electromagnetic instrument calibration system comprises a control system, a multipath transmitter and a casing, a plurality of groups of coils capable of transmitting or receiving electromagnetic signals are wound outside the casing, and the turns of the plurality of groups of coils are different to simulate different rock skeletons; the control system comprises a stratum database which can transmit and collect voltage signals; the multipath transmitter is connected with the coils and the control system. The multipath transmitter is used for converting voltage signals of the control system into electromagnetic signals of the corresponding coils. During the calibration, different voltage signal instructions are adjusted through a control system, so that a plurality of groups of coils with different turns