With the formation of the large power grid, the security of the network is particularly important. The pollution flashover of insulators is a serious impact on the operation safety of high voltage power network. In this paper, the characteristics of the pollution flashover of insulators are analyzed, and the correlation between the sound signal and the insulator pollution flashover is found. The pollution flashover of insulator is analyzed by wavelet packet analysis, and the characteristics of the pollution flashover are obtained.