Abstract: The ultrasonic testing signal of multi-layered metal structure includes a mass of noise, and the noise submerges completely the useful flaw signal. Morlet-P wavelet was constructed during the multi-scale analysis. When more than one scale parameter was applied to the continuous wavelet transform based on the Morlet-P wavelet, the wavelet transform coefficient still included the flaw characters. So the shortcoming of multi-resolution analysis on the narrowband signal was overcome.