Abstract: For the ultrasonic testing signal of a multilayered interface structure specimen in the solid rocket engine, the Wavelet transform module maximum were used to pick-up the signal characteristic and figure out the Lip index of signal singularity. These extracted features were effective for the analysis of the multilayered interface structure and identification of the bonded properties in the solid rocket engine. It was hoped to provide considerable promise in the multilayered bonded structure testing area by ultrasonic testing.