The invention discloses a field calibration method of a non-contact type transient voltage measurement device of an alternating-current substation. High-voltage transient voltage is applied to three-phase conductor wires in sequence; the composite transformation coefficient of the measurement device is obtained by utilization of the transient voltage on three electric field sensors and the three-phase conductor wires; field calibration on the measurement device is completed; the gap of the field calibration technology of the non-contact type transient voltage measurement device of the alternating-current substation is filled; because influence of the three-phase conductor wires on the electric field sensors is considered in field calibration, the transient voltage measurement accuracy of apower transmission line can be ensured; and thus, the method has great important meaning for monitoring the alternating-current substation.