Abstract: An improved Hilbert-huang transformation (HHT) method based on bandpass signals is proposed for the identification of modal parameters of civil engineering structures, which is combined with the bandpass filter technology of wavelet packet transformation, efficiently restraining the phenomenon of modes mixing in empirical mode decomposition (EMD). To avoid the endpoint effect in the process of EMD and bandpass filter, the method of eliminating endpoints is adopted and it improves the reliability and stability of algorithm. The experiment modal analysis was conducted on a reinforced concrete frame structure, which is inspired by a pulse excitation, and compared with the theoretical calculations. The identification results show that the model considering node rotation is more accurate to reflect the dynamic characteristics on the transverse vibration of the structure.