The resonant grounding system is widely used in the power grid system, so the resonant grounding system of single-phase grounding fault line selection has been researched the hot problem. In view of the existing resonant grounding of the defects in the system of fault line selection method, based on short-term put in the parallel resistance,improve transient characteristics of component line, this paper puts forward an optimization scheme. The resistance which in parallel with the Petersen coil has been controlled by the SCR, and it can enhance the fault characteristic signal. To determine the fault line, the extraction of zero-sequence current transient signal to wavelet transforms, detection the singularity of signals after decomposed and reconstructed. The simulation results show that the scheme is correct.