Abstract: On the basis of the experimental study for two dimensional seismic model, the relations between the pattern of p-wave radiation, fault movement and tectonic stress are revealed by three dimensional seismic model, simulating the initial motion of actual faults. In studying the characteristics of propagation and radiation pattern of p-wave, it is inferred that the generating mechanism of an actual earthquake can be well explained by single lateral propagation of a fracture with finite displacement.