In order to research the influence of pulse-width on stimulated Brillouin scattering(SBS)phase conjugation fidelity,experiments were performed on three different SBS media CCl₄,N-hexane and CS₂. The method of array camera is used under the conditions that pulse-width is respectively 12 ns,7 ns,2 us. Experimental results show that pulse-width has a great influence on SBS fidelity. The fidelity value of SBS has higher standard,and more stability when pulse-width is a greatly larger than phonon lifetime;It gradually falls down when pulse-width equals to phonon lifetime;It declines rapidly and has strong fluctuation when pulse-width is less than phonon lifetime.