The invention discloses a voltage sag event normalization method based on waveform characteristics. The voltage sag event normalization method comprises the following steps of S1, acquiring A, B and Cthree-phase voltage amplitudes by utilizing a voltage monitoring device; S2, filtering zero-sequence voltage of A, B and C three-phase voltage amplitudes to obtain A, B and C three-phase voltage andA, B and C three-phase line voltage; S3, judging a sag type according to the A, B and C three-phase voltage and the A, B and C three-phase line voltage; S4, according to the A, B and C three-phase voltage amplitudes, calculating the segment similarity of events of the same sag type; S5, obtaining an initial similarity set according to the segment similarity of the events of the same sag type; andmining and correcting the influence of the transformer based on the association rule, outputting a normalization identification result, and completing normalization processing of the voltage sag event. According to the method, the influence of the monitoring device on the time error is overcome, the method does not completely depend on the criterion of the voltage sag occurrence moment, the sag waveform characteristics are considered, normalization identification is carried out by taking the sag waveform characteristics as the criterion, and the accuracy is high.