Accurate identification of lightning fault is of great significance for improving the transmission line lightning protection design. In this paper, the three-phase travelling wave current is studied. Based on the wavelet energy spectrum, a lightning fault identification method is established. According to the distribution characteristics of wavelet energy spectrum for different lightning faults, the corresponding characteristic and fault identification criterion are constructed. The simulation results show that, the method is not affected by parameters and waveforms of lightning current models. It can distinguish accurately the three fault types, which is shielding failure without flashover, shielding failure with flashover and back flashover. By choosing the threshold value and setting the detection point reasonably, it can respectively avoid the effect of lightning impulse corona and reflected wave at the end of the line on the accuracy of the method. Thus, the method has high practical value.