Abstract: Stimulated Brillouin Scattering (SBS) is a third-order nonlinear optical effect, the reflected beam of which has the property of phase conjugation. The reflected beam is time inversed on amplitude, phase and polarization with the incident beam and maintains the same wavefront as the incident light. In the Master Oscillator Power Amplifier (MOPA) nanosecond laser system, the thermal effect in the laser amplifiers and a large number of optical elements in the optical path cause serious wavefront distortion of the transmitted beam, which not only deteriorates the beam quality, but also limits the possibility of further power improvement. Stimulated Brillouin Scattering Phase Conjugate Mirror (SBS-PCM) is utilized widely in this kind of laser system for the fact that using SBS-PCM by making the beam transmit along a round trip in amplifiers which bring in serious wavefront distortion compensates the distortion in real time, therefore is capable of optimizing the beam quality and improving the output power, so as to promote the development of nanosecond laser system in the direction of both high power and high beam quality. In this paper, the basic principle and phase conjugation characteristics of SBS-PCM were briefly introduced theoretically. Then the characteristics and application scope of different SBS-PCM media were compared. The research progress by domestic and foreign institutions on SBS-PCM and the typical application and development process of SBS-PCM in high power nanosecond lasers were summarized. Finally, the development trend of SBS-PCM was prospected.