针对多模光纤的分布式传感系统受多模光纤布里渊散射特性的影响，利用有限元仿真得到多模光纤6种典型传输模式的电场分布，并从布里渊频移、线宽、峰值增益和布里渊散射谱4个方面仿真研究了单一模式和模式叠加情况下多模光纤的布里渊散射特性。仿真结果表明: 多模光纤不同传输模式的线宽和增益峰值都随着模式阶数的增加略有减少，布里渊频移随模式阶数减小而明显增加；在不受应变和温度影响的情况下，多模式叠加后布里渊散射谱相较单一模式线宽发生展宽，增益峰值大幅减小。

Aiming at the distributed sensing system based on multimode fiber is affected by the Brillouin scattering characteristics of multimode fiber, this paper uses finite element simulation to obtain the electric field distributions of six typical transmission modes of multimode fiber, and the Brillouin scattering characteristics of multimode fiber under single mode and mode superposition are simulated and studied from four aspects: Brillouin frequency shift, linewidth, max gain and Brillouin scattering spectrum. The simulation results show that the linewidth and max gain of different transmission modes of multimode fiber decrease slightly with the increase of the mode order, while the Brillouin frequency shift decreases significantly with the decrease of the mode order. Unaffected by strain and temperature, the Brillouin scattering spectrum after mode superposition is broadened compared to the single mode linewidth, and the max gain is greatly reduced.