The physical model of perilous rock avalanche excitation effect is deudofed based on the effect of the main factors, such as weight and fissure water pressure. It quantizes the interaction of perilous rock masses through the energy point of fracture mechanics and wave theory, and gains the departure rate formula of landslide body at momentary avalanche. The particle displacement rate calculation method of perilous rock medium under the action of excitation waves is developed based on the formation of perilous rock avalanche excitation waves and the spread mechanism in slope rock formation. The example shows that the analysis results established are coincident with actual situation. Some scientific basis is provided for the further research of perilous rock damage and evolutionary mechanisms.