The influence of configuration parameters in a one-cell system on the pulse waveform of stimulated Brillouin scattering was investigated experimentally. The Stokes pulsewidth was easily changed from 1.5 to 8 ns by varying the lens focus and the distance between the lens and the SBS cell. The SBS pulse waveform was numerically simulated by the theory model of stimulated Brillouin scattering initiated by thermally excited acoustic waves. The theoretical calculation was coincident with experiment results well.