Abstract: For the aircraft cockpit background sound analysis in civil aviation accident investigation, the wavelet packet analysis method is used to carry out the time-frequency analysis of the different types of switches’ sounds, and extract the bands normalization energy characteristics which can be applied to identify various types of switches sounds. Finally, the typical switches sounds for the B737 aircraft are acted as the research objects, and a number of samples coming from various types of switches sounds are collected from experiments. The sounds samples are analyzed and the energy features are extracted and the results are statistically verified which are fully show the validity of this method.