管道作为石油、天然气、自来水等的主要运输工具，其运行安全性已受到广泛关注。管道腐蚀穿孔引起的持续性小规模泄漏的及早发现与准确定位是管道运行安全的主要问题和难题。利用Sagnac光纤干涉仪对管道小泄漏进行监测和定位时，光波偏振态的随机变化直接影响到Sagnac环中两束相干光的干涉效果，从而影响直线型Sagnac光纤干涉仪的性能。提出了采用光学消偏的方法抑制偏振态对Sagnac干涉仪性能的影响。通过改进干涉仪的结构，在Sagnac环中加入光纤延时环消偏器，从而提高系统运行稳定性。实验结果表明，该方法能够较好地解决偏振态变化引起的检测灵敏度降低的问题。

As the main transportation facilities, such as petroleum, natural gas, city water, and among others, the pipeline has been concerned extensively for its safety in operation. Meanwhile, to find and locate the positions of the persistent small-scale leakage of the pipeline is one of the major issues and difficulties faced by the safe operation of the pipeline. When Sagnac fiber interferometer is in the use of monitoring and positioning of a small leak on pipeline, the interference result of the two coherent laser beams in Sagnac ring will be affected by the random change of light polarization, thereby affecting the interferometer performance of linear Sagnac fiber optic interferometer. A new method is proposed to suppress the influence of random change of polarization on Sagnac interferometer. By modifying the structure of interferometer, an optical depolarizer is introduced into the Sagnac ring to improve the operational stability. Experimental results show that this method is a good solution to solve the deterioration of sensitivity caused by polarization fading.