Based on the Hilbert-Huang Transform (HHT) and its marginal spectrum, an energy-based method for analyzing the dynamics of earthquake-induced landslides is proposed and a case study is presented in this study. The research results show that the seismic energy in the sliding mass is larger than that in the sliding bed when subjected to seismic excitations, causing different dynamic responses between the sliding mass and the sliding bed, which may be the most essential reason for the dynamic failure in the weak zone. The seismic energy moves from the high frequency components towards the low frequency components when the seismic waves propagate through the weak zone, causing nonuniform seismic energy distribution in the frequency domain. Shear failure develops first at the crest and the toe of the sliding mass due to the resonance effect, meanwhile, the seismic energy carried in the frequency components of 3-5 Hz, which is close to the natural frequency of the slope, is significantly dissipated in the initiation and failure processes of the landslide. With the development of dynamic failure, the peak energy transmission ratios of the weak zone decrease gradually. The study in this paper offers an energy-based interpretation for the initiation and failure mechanism of earthquake-induced landslides with the shattering-sliding failure type.