In order to analyze the energy distribution of the seismic response signal in differ rent frequency bands that have distinct non-stationary characteristics, according to the actual seismic monitoring data, the wavelet packet analysis, which has good characteristics of time-frequency localization and a uniform band division capacity, is used to analyze the Ertan dam seismic response signals. First, the similarities and differences between the wavelet transform, wavelet packet transform and the choice of mother wavelet are briefly introduced, and the concept of wavelet frequency-aliasing index is proposed and selected as an index of choosing the mother wavelet. Second, the differences in energy distribution of response signals from different locations and directions which is expanded in different frequency bands are discussed. Finally, the relationship between location, direction and energy distribution is obtained. The results provide a theoretical basis for the seismic analysis of dams, as well as for energy-related safety assessment methods.