Abstract: Based on the theory of the one-dimensional nonlinear interaction between elastic wave and contact surface, a nonlinear stiffness model using contact pressure to describe nonlinear stiffness characteristics is established. One-dimensional composite wave incidence including fundamental and harmonic waves is introduced, the expressions of reflection wave and transmission wave at the interface are derived by the second order perturbation approximation and under the nonlinear boundary condition, and the reflection and transmission coefficients are obtained. By the power-law relationship between the linear stiffness of interface and the contact pressure, four nonlinear parameters are defined. The nonlinear characteristics of solid-solid contact surface and the dependency of the harmonic waves on the contact pressure are analyzed by numerical calculation.