The invention relates to a power distribution network initial fault locating method and early warning method. The transient zero mode current signal on each feeder line is extracted by using a transient traveling wave detection sensor to perform morphological filtering so as to eliminate the high frequency noise; S-transform is performed on the signal after elimination of the high frequency noiseso as to obtain the time of arrival of the fault traveling wave header; first-order differential processing is performed on the corresponding data near the sampling value of the time of arrival obtained by each feeder line so as to obtain the wave header polarity of each feeder line; the wave header polarity of each feeder line is compared and the line having the opposite polarity to other lines is selected; after the fault feeder line is selected, the transient traveling wave signal detection sensor transmits warning information, and the upper computer obtains the class of the warning type ofthe transient traveling wave signal detection sensor from the warning information; and the upper computer determines the transient traveling wave signal detection sensor corresponding to the fault feeder line according to the warning class. The influence of the high frequency noise on the transient traveling wave signal detection sensor can be effectively avoided and the accuracy of the detectionfault point can be effectively enhanced.