Harmonic balancing method has more powerful superiority than other perturbation methods in the respect of solving steady-state response of strong nonlinear system. The amplitude-frequency equation of dry-friction vibration system considering cubic nonlinear displacement under harmonic excitation was derived by harmonic balancing method. Because the effect of even nonlinear term on vibration response of system was not evident, even nonlinear term of elastic restoring force was neglected. The first term coefficient and third term coefficient obtained by static experimental data for constitutive relationship of metallic rubber were substituted into frequency response equation. Amplitude-frequency characteristics curves of vibration response for cubic nonlinear displacement dry-friction system of metallic rubber were obtained. Natural frequencies obtained by computation were compared with natural frequencies by experiment, and the two Natural frequencies consisted with each other. It showed that the method that vibration response for cubic nonlinear displacement dry-friction system of metallic rubber was computed is reasonable.