The utility model provides a heavy current transient characteristic detection apparatus of electronic current transformers, comprising a transformer, a direct current charging power supply and a waveform output unit in connection with an ECT sample; the waveform output unit comprises a stable state waveform output unit and a transient waveform output unit. Compared with prior art, the heavy current transient characteristic detection apparatus can perform precise adjustment on current peak values and fall time constants of outputted transient voltage waveforms and transient current waveforms to meet test requirements of electronic current transformer samples of different models.