To achieve accurate single-phase ground faults for the complex system with multiple feeders and cables co-existing with overhead lines, we model it with PSCAD and run diverse simulations of single-phase ground faults on each line. The simulation data was analyzed by wavelet toolbox in Matlab. At first, the modulus maxima are obtained, after the wavelet decomposition, to determine the beginning of fault. Then, the wavelet packet decomposition coefficient is used to determine the polarity relationship of the zero-sequence current between the non-faulted line and the fault lines. Finally, the fault measure is used as the selection criterion, and the line corresponding to the maximum value of the fault measure is the fault line. After a large number of experiments, it can be concluded that the fault line selection process is correct and reliable, and it has strong anti-interference ability.