There is a problem that the decrease in accuracy of single-phase grounding fault line selection is because of a large number of cable lines in the resonant earthed system. To solve this, a fault line selection method is proposed based on calculating the reconstruction error of the transient zero sequence current of lines and the multi-scale cross-sample entropy of the transient low frequency bands. Because of the compensation effect of the arc suppression coil, the change of phase and period of transient zero sequence current in a fault line are different from those of a sound line when single-phase grounding occurs in a resonant earthed system. Using the principle of different phase changes, the transient zero sequence current is reconstructed by inverse synchrosqueezed wavelet transforms and the error is calculated. According to the principle of different period changes, the multi-scale cross-sample entropy of the low frequency bands of the transient zero sequence current is calculated. The fault line is determined when the sum of reconstruction errors and the cross sample entropy are at a maximum. A large number of simulation results show that the method is less affected by different fault conditions, and has high reliability and strong anti-interference. This work is supported by the National Natural Science Foundation of China (No. 61761049).