The invention discloses a method for measuring electric network voltage flicker, and discloses a high-accuracy rapid flicker calculating method aiming at a non-integral cycle low sampling rate by taking account of errors probably caused by harmonic waves and electric network frequency. The core of the calculating method is that: a low fixed sampling rate is adopted to perform non-integral cycle sampling on electric network voltage waveforms, a cosine window is used for performing a fast Fourier transform algorithm (FFT), then the flicker frequency component is accurately extracted through a double-spectral line interpolation algorithm and a frequency spectrum searching algorithm, and the instantaneous flicker visual sensitivity is obtained through calculation. By using the method, under the condition of non-integral cycle low sampling rate, the errors caused by frequency spectrum leakage and harmonic wave aliasing are overcome, the frequency resolution is improved, the complexity of flicker calculation is effectively simplified, and a flicker measurement result is acquired quickly. By using the method, the performance requirement of hardware of an analog-digital converter, a processor and the like is reduced, thus the cost of a flicker measuring instrument is reduced, and simultaneously the measuring accuracy is improved; and besides, the method is applicable to fast low-cost measurement of the electric network voltage flicker, and has a very good effect.