Abstract: When a single-phase grounding fault occurs in the coal mine 10 kV power supply system, due to the low sampling frequency of the system, the traditional transient line selection method is easy to lose the “line selection information”, and is greatly affected by the initial phase angle of the fault and the high-resistance grounding, which eventually leads to line selection error, seriously restricts the speed of power restoration after the fault; in this paper, the “line selection method through the polarity of stacked pulse” is proposed, which uses the opposite polarity of the stacked zero-sequence current points and combines the proportion of effective points to select the line. Combined with the single-phase-grounding fault of the ground 10 kV power supply system in Pingshu Coal Mine, Matlab/Simulink simulation verification was carried out. The results show that the method is not affected by the initial phase angle of the fault, grounding resistance and whether the “line selection information” is omitted, and the line selection results are accurate and reliable.