The zero-sequence characteristic difference between faulty line and healthy line is weakened by resonant grounding system, so a line selection method based on transient zero-sequence admittance is proposed in this paper. Firstly, the transient zero-sequence admittance formulas of faulty line and healthy line under single-phase grounding fault are deduced theoretically, and the characteristic differences between them are compared. On this basis, a single-phase grounding fault line selection method based on the maximum mean value index of transient zero-sequence admittance is constructed. Finally, based on PSCAD/EMTDC software, the performances of the proposed method are verified and tested comprehensively. The results show that proposed method has the advantage of strong resistance tolerance to the transition resistance. Only the transient zero-sequence admittance in half power frequency cycle after the fault needs to be calculated, so the calculation load is small, the speed is fast and the implementation is easy. At the same time, the line selection accuracy is still high under the interference factors such as noise interference, current transformer reverse connection, the changes in network topology, line parameters and sampling frequency.