Abstract: A two-degree-of-freedom impact system with a clearance and pre-compressed spring is studied. The Poincaré map and its Jacobian matrix are constructed for analyzing the stability of the system. The periodic and aperiodic motions of the system are investigated, and verified by Lyapunov exponents. The parameter regions, where a boundary grazing phenomena may happen, are predicted by a test function. The phenomena of period-doubling and Hopf bifurcations intermitted due to boundary grazing motion are investigated. The changes of the eigenvalues, determinants and traces at the grazing points due to border collision are analyzed.