In the paper, a solid- state master oscillator amplifier (MOPA) system is built, which consists of a single-longitudinal-mode resource pumped by semiconductor, three amplifiers pumped by xenon lamps which beam light passes double times and the phase conjugating SBS-mirror to compensate the phase distortions. In this laser system, image transfer, thermal depolarization compensation, elimination of self-lasing and other key technologies are employed to improve the quality of the output beam. In addition, the output energies over 450 mJ are attained at 40 Hz, with output energy stability of 3.5% (RMS), the pulse width about 8 ns, and mode quality <1.3DL.