High impedance fault is always difficult to be identified due to its unobvious fault signature and difficult detection. This paper decomposes the transient signal in multi-scale by utilizing the good localization performance of the wavelet in both time domain and frequency domain，reconstructs the wavelet coefficients under each scale，takes the wavelet reconstruction coefficient under the scale of 3，calculates the size spectrum of each feeder line in timing floating window and identifies the circuits in which the faults lined according to the value of the size spectrum. A high impedance fault simulation system is built based upon the study of the various transient signals in power systems，and the high impedance fault simulation analysis of the distribution feeder is undertaken through PSCAD simulation platform using high impedance fault model. Simulation analysis shows that the method can effectively extract the feature of high impedance fault on high impedance fault identification.