Laser beam focused on stimulated Brillouin scattering (SBS) medium can produce phonon grating, whose density contrast direct ratio to superposition fringe intensity contrast of light field. Then the reason of broad-band laser SBS having higher energy threshold than narrow-band SBS is analyzed, and the qualitative analysis of broad-band SBS phase-conjugation laser resonator having higher startup energy threshold is given. A broad-band SBS phase-conjugation laser resonator of CrLiSAF is designed and operated, its free-running output laser pulse waveform, self-Q-switching output laser pulse waveform, pulse energy and beam divergence angle are measured. The results indicate that this resonator can produce 50 ns self-Q-switching narrow pulsewidth laser beam efficiently, its beam divergence angle is compressed by a factor of two.