The invention relates to a small current earth fault line 
selection method for a 
radial distribution network. The small current earth fault line 
selection method for the 
radial distribution network comprises the steps that firstly, the line reference values of fault lines and non-fault lines are calculated according to the number of 
branch lines of a current 
radial distribution network 
system; secondarily, taking a Gabor atom dictionary as the index, a matching tracing 
algorithm is utilized to carry out time frequency atomic 
decomposition on transient zero-sequence current of each fault 
branch line within the first one quarter cycle, and attenuation sinusoidal quantity atoms representing the fault feature information of 
branch lines are further obtained; thirdly, an improved gray correlation analytic method is adopted to carry out correlation degree analysis on the attenuation sinusoidal quantity atom of each 
branch line, so that the feature value of each 
branch line is obtained; and finally, 
Euclidean distance is obtained by using the feature value of each 
branch line and the reference values of the fault lines and the non-fault lines, the Euclidean distances are compared, so that the accurate line selection is realized through the comparison of the Euclidean distances. The small current earth fault line 
selection method for the radial distribution network realizes low calculated amount and high line selection accuracy and is particularly applicable to radial distribution network systems with multiple branch lines.