Abstract: Through deep analysis of stable state and transient state process of grounding fault in distribution network and combining with wavelet packets theory,the paper put forward a new method of single-phase grounding line selection in distribution network based on the wavelet packet and energy,introduced base,principle and procedure of line selection of the method.The simulation experiment of Matlab(indicated) that the line selection method enhanced accuracy and reliability of grounding fault line selection,(which) had good application worth.