为了研究抽运光的脉冲宽度对布里渊散射光的影响，对光纤传感系统中基于受激布里渊散射的三波耦合方程进行了分析，采用频域分析和一种微扰近似理论推导了散射光的近似表达式，然后通过数值计算分析了散射光随着脉冲宽度的变化规律。结果表明，在宽度接近于20ns(声子寿命)的脉冲下，散射谱出现多波峰结构；当宽度越来越接近于40ns时，主波峰逐渐增大，次波峰逐渐减小；当采用的脉冲宽度远远大于声子寿命时，散射谱只出现一个波峰并且维持一个波峰不变。此研究为传感中选取合适的脉冲宽度提供了参考。

In order to study effect of pulse width of pump light on Brillouin scattering light, three-wave coupling equations of stimulated Brillouin scattering in optical fiber sensing system were researched. The approximate expressions of scattering light were deduced based on frequency domain analysis and perturbation approximation theory. The influence of pulse width on Brillouin spectrum was analyzed through numerical calculation. The results show that a multi-peak structure of Brillouin scattering spectrum is gotten when the width is close to 20ns(phonon lifetime). When the width is more and more close to 40ns, the main peak increases and the sub-peak decreases gradually. When pulse width is far greater than phonon lifetime, scattering spectrum appears only one peak and maintains a constant peak. The study gives references for the choose of suitable pulse width in sensing.