小电流接地系统发生接地故障时，利用prony算法提取暂态特征分量并利用相关分析法实现选线取得很好的效果，有效的排除了干扰信号的影响，结论明显、准确性高。-When the small current grounding system occurs ground fault , we use prony algorithm to extract the transient characteristics of the component and line selection by using correlation analysis. The simulation present that the algorithm　effectively eliminate the influence of interfering signal. The result has a good effect and high accuracy obviously.