The invention relates to a distinguishing method of true and false frequency multiplication pressure pulsation signals. The method comprises the following steps: ascertaining basis parameters of waterpower mechanical equipment, ,working condition parameters during pressure pulsation testing, and measuring positions and a measuring analysis method of pressure pulsations; searching for false frequency multiplication components, through comparison with waveform and frequency spectrum curves of pressure pulsation signals, eliminating false components which may be "fabricated" by various sawtooth waves, examining whether pressure pulsation waveforms "fabricate" these frequencies according to frequency multiplication conditions, and making a frequency list of suspecious false multiplied frequencies; and through comparison with measured conditions of the pressure pulsation waveforms and physical parameters of the waterpower mechanical equipment itself, determining whether physical elements generating the previously listed suspecious false multiplied frequencies exist so as to determine whether these frequency multiplication components are true or false. The method provided by the invention effectively eliminates the influence of false frequency multiplication "fabricated" by FFT, can more efficiently and directly guarantee stable and safe operation of a generator set, and can be widely applied to the fields of similar periodical signal analysis as vibration, swing and the like of rotation machinery.