Abstract: The distribution network is grounded through arc suppression coil. When a single-phase grounding fault occurs, the faulting characteristics are often weak and unobvious, which makes it difficult to accurately locate the fault line. In recent years, with the development of communication and other related technologies, the cost of differential protection has decreased continuously, which makes it possible to realize the differential protection of distribution network. Therefore, a line selection method based on variational mode decomposition (VMD) and Duffing oscillator system is proposed. Firstly, the high-frequency component of transient zero-sequence current is obtained with VMD, and the phase difference of high-frequency zero-sequence current on both sides of the line is added to the Duffing system. And then, by analyzing the relationship between the phase difference of high-frequency components on both sides of the line and the state of the Duffing system, a fault criterion based on dynamic time warping (DTW) is constructed to realize the accurate location of the fault. Finally, numerical simulation proves that the proposed line selection method can quickly and accurately locate the single-phase ground fault sections for the lines that have different transition resistances and distributed power sources. The proposed fault section localization algorithm can effectively extract fault characteristics, thereby improving the reliability of protection and the accuracy of line selection.