Abstract: In this paper an experimental study on self-demodulation of the pulse train with sinusoidal carrier is presented.Some results are as follows:(1) when the duration ratio is less than 1,parametric pressure has a maximum and minimum varying with increasing of duration ratio,and the number and location of extreme values are dependent on the repetition frequency,the center frequency of the filter and its band-width,(2) if the duration ratio is so little that the width of a single pulse in the train is quite narrow,the waveform of the parametric signal will be unsymmetrical about the time axis and (3) in case of the duration ratio being equal to one,its parametric waveform will become two N-shape pulses located at the edges of primary pulses respectively