This paper investigated the coupling dynamics between the rigid-bodies and the bulk solids bed in the vibratory crusher.First the relationship of the bulk solids bed during pressing and releasing was studied by the specially designed experiments.Then the governing equations of the crusher were derived according to the Lagrange's method,and its dynamical performance was investigated by solving these equations by Runge-Kutta Method,so the effect of the bulk solids bed on the trajectory of the four moving jaws was explored.Finally some dynamical experiments were carried out,which agreed well with the numerical nanlysis.Therefore all of the work provides a basis for the dynamics design and development of the new vibratory crushers.