Using optical nber with diameter of 0100 mm and ￠200 mm as phase-coryugator, the energy reflectivity, stability, fidelity and output energy in ΜΟΡΑ system of four-pass configuration are presented Applying optical fiber of 0100 mm core diameter, 6 mJ output energy and 41% SBS reflectivity have been obtained, SBS threshold is 0.73 mJ. Applying optical fiber of 0200 nun core diameter, 21 mJ output energy and 37% SBS reflectivity have been obtained, SBS threshold is 1.1 mJ.