Abstract: The traditional wavelet transform has some limitations in analyzing transient signals, which are accompanied by high frequency carriers. These limitations can be overcome byM-band wavelet transform. The construction conditions ofM-band wavelet base are discussed. Then, a newM-band wavelet base construction method based on cosine modulated perfect reconstructing filter group is proposed. A 6-band wavelet base is constructed, its time and frequency characteristics are studied, and the local discharge transient signals are analyzed. The wavelet transform results of the transient indicate the advantages of the proposed method.