In this paper, the pulse waveform of stimulated Brillouin scattering (SBS) is investigated experimentally and theoretically. The variations of SBS pulse waveform with pump parameters, structural parameters and medium parameters are experimentally investigated with a Nd∶YAG Q-switched laser，and numerically simulated using SBS theory model. The theoretical calculations are in good agreement with the experimental results. The results indicate that modulation of pulse waveform is difficult to realige with low pump energy, short focal length, long lens-cell distance and long phonon life time. The influence of the pump parameters, structural parameters and medium parameters on SBS pulse waveform is discussed extensively.