In this paper， the global dynamics of chaos and subharmonic bifurcation of an impacting system of cantilever beam sup? ported by oblique springs under bilateral asymmetric rigid constraints are studied. It is difficult to study analytically the chaos and subharmonic bifurcation of the system because the stiffness term of the oblique spring support structure is a transcendental function. To do this， the stiffness term of the system is fitted by the approximation method， and the homoclinic orbit and its internal orbits of the approximate system are compared with the orbits of the original system. The threshold conditions for homoclinic chaos and sub? harmonic bifurcation are presented by applying the Melnikov method to the non-smooth impacting cantilever beam system. More? over， the stability of the impacting subharmonic orbit is analyzed by combining characteristic multipliers of smooth manifolds with impact function， and the relationship between subharmonic bifurcation and chaos is analyzed. The effects of damping， excitation frequency， excitation amplitude and impact coefficient of restitution on chaos and subharmonic bifurcation are studied based on threshold conditions， which further verify the theoretical analysis.