受激布里渊散射（SBS）效应是影响连续波单频光纤激光放大器功率提升的重要因素，就传能光纤长度对连续波单频全光纤激光放大器SBS阈值功率的影响进行了实验研究。采用线宽为2.35 kHz的非平面环形腔(NPRO)结构种子光源，搭建了两级级联单频连续波全光纤激光放大器，通过改变主放大器增益光纤与输出光隔离器之间传能光纤的长度，检测主放大器回光功率和光谱随输出激光功率的变化，分析了无源传能光纤长度对连续波单频全光纤激光放大器SBS阈值功率的影响，实验结果与理论计算结果相符。

Stimulated Brillouin scattering (SBS) is an important factor that affects the increase of output power of single-frequency fiber amplifier. The impactions of length of transmitting fiber on the SBS threshold power of continuous-wave single-frequency all fiber amplifier are experimentally studied. Two stage continuous-wave all fiber amplifier is set up with the seed line-width of 2.35 kHz. By changing the length of the transmitting fiber between the gain fiber and the output isolator, the power feedback and spectral feedback of amplifier as a function of output power are measured, and the impactions of the length of transmitting on SBS characteristics of all fiber single-frequency laser are analyzed. The experimental results match very well with the theoretically calculated results.