The reliability of selecting the power lines of single-phase fault in small current grounding system is rather low because the fault current is too little, the electric arc is unstable, the electromagnetic interference is strong and the SNR is low. The paper utilized wavelet transform to extract the transient Special Frequency Band (SFB) of zero sequence voltage and current. Because the transient current directions between faulty feeders and healthy feeders are opposite in SFB, the transient Reactive Power algorithm is selected for the fault feeders selecting. The simulation and analysis by MATLAB verified that the proposed method can exactly distinguish single-phase grounding fault feeders and it has higher reliability and sensitivity.