In order to solve the problem that the accuracy of transient fault line selection method of resonant earthing system is not high, a small current fault line selection method based on the coefficient of variation and high order cumulant is proposed. First, the initial polarity of the fault component of zero-sequence current is solved using the coefficient of variation. If it is a line fault, the zero-sequence current of each outgoing line is decomposed by means of variational mode decomposition, and the DC component and power-frequency AC component of zero-sequence current are extracted. Finally, the dual polarity selection is realized by combining the high order accumulator of the DC component and the initial polarity construction criterion of the AC component of the power frequency. Simulation results show that this method is not affected by fault closing angle and transition resistance. This work is supported by National Natural Science Foundation of China (No. 61703144) and Science and Technology Key Project of Henan Province (No. 182102210051).