Abstract: Using piecewise linearity system theory, the nonlinear response of a clearance-restriction cantilever beamsystem to a harmonicexcitation is researched. Firstly, the dynamic model of this system is built.Based on the transmission function, the dynamical equation and itssolution are derived. The obtained numerical solution show the changefeature of the dynamic response character with the excitation frequency,excitation amplitude, contact rigidity and contact dumper.