Based on analysis of transient characteristics of zero-sequence signals which occurs in a single-phase to earth fault of the resonant earthed system， the relations among energy distributions of spectrum， fault time and transient resistance of zero-sequence current signals are built. Based on the wavelet packet decomposition for the zero-sequence signals， the definitions of energy ratio factor and transition factor are given. And a new adaptive feeder selection method with both factors for single-phase-to-ground fault is proposed. All information of the transient zero-sequence currents such as: low frequencies， fundamental frequencies and high frequencies are adopted in this method， which may adaptively select fault feeder in the most apparent characteristic bands. It can also successfully distinguish the bus faults from high-impedance earth faults. Theory analysis and simulation results prove the accuracy and feasibility of the proposed method.