Abstract: The wavelet packet impulse response function and wavelet packet energy spectrum of the structural dynamic system are proposed to reflect the structural dynamic characteristics, which is obtained by the wavelet packet decomposition of vibration stimulation signal and response signal based on the combination of vibration testing and wavelet packet analysis. Through a vibration testing analysis of a reinforced concrete slab subjected to static loading series, the damage status of the slab during different loading phases are determined based on the calculation of wavelet packet impulse response functions and wavelet packet energy spectrum. The proposed method overcomes the shortcoming that wavelet packet energy spectrum calculated directly from structural dynamic response cannot reflect the structural dynamic characteristics and the experiment results confirmed the feasibility of the method.Key words：damage alarming; vibration testing; wavelet analysis; wavelet packet analysis; wavelet packet energy spectrum