The air suspension nonlinear vibration was researched in this paper. The nonlinear vibration differential equations of air suspension were established, and theoretic research and test validation were carried out. There will be resonance vibration for linear spring suspension when pumping frequency equal to natural frequency. But for air suspension nonlinear vibration, the output frequency is integer multiples of the pumping frequency. The air suspension vibration wave's mid-position is not on s=0 point. The vibration wave is dissymmetric to the equilibrium position.