In order to evaluate the insulation status of transmission line and ensure power system stability, a method is proposed to identify several flashover factors for the transmission line insulation in this paper. Firstly, the impact test platform superimposed by the power frequency is utilized to simulate three types of transmission line faults to obtain flashover current data. Secondly, the flashover current signals are transformed into reconstructed signals in different frequency band using the wavelet transformer. Finally, the wavelet energy spectrum is used to construct the highfrequency energy center of gravity as the identification feather, combined with the low frequency energy value to propose a comprehensive identification criterion. Furthermore, three types of inducement data are analyzed and distinguished. The results show that these three flashover under power frequency superimposed shockspollution, icing and vegetation flashover, can be accurately identified by the proposed method, and the correct identification rate can reach 91.1%.