A time-frequency joint algorithm based on EEMD(Ensemble Empirical Mode Decomposition) and Choi-Williams distribution was put forward. The algorithm decomposed signals into a aggregation of several Intrinsic Mode Functions in the frequency domain adopting the EEMD algorithm.Then processed the components with the Choi-Williams distribution and the time-frequency distribution characteristics of signals could be obtained.The algorithm could eliminate the cross terms of the IMF within the signal and get the nature correlative characteristics of the signal.Through the joint time-frequency analysis of acceleration signals which is measured in Penetration of two concrete targets of different thickness using EEMD and Choi-Williams distribution

the conclusion that the stimulated vibration modes of the projectile are related with the thickness of target and the speed when the projectile contacts with the target.