The invention discloses a partial discharge phase identification method based on a radar spectrogram. The method is characterized by carrying out transformer partial discharge experiment; measuring the waveform of partial discharge pulses in oil-paper insulation equipment to be measured based on existing technology; carrying out processing on the sampled oil-paper insulation partial discharge waveform, and extracting apparent discharge of partial discharge, phase of the discharge pulses, continuous pulse time interval and discharge repetition rate (discharge times per power frequency period);and calculating pulse equivalent time and equivalent frequency according to the recorded partial discharge time-domain waveform, wherein the equivalent time and the equivalent frequency reflect partial discharge waveform features.