Abstract: A mechanism model of infrasound producing in earthquake incubating was proposed, in which interaction between atmosphere and deformation of Earth surface generated by dynamic behavior of geologic bodies in the final stage of earthquake incubation causes the observable infrasound. As an example to verify the model of geological behavior an earthquake in the Northeast area of Japan was modeled numerically and analyzed by two dimensional finite element method (FEM). A layer geological model and effect of the Pacific subducting plate were included in the numerical model. Based on the dynamic coupling theory between structures and fluids, infrasound was obtained by numerical simulations. Good agreement between the observed and the simulated suggests that the proposed model is reasonable.