Air damped rubber mount (ADM) is a new kind of vibration isolator for automotive powertrains and other dynamic systems, and the dynamic characteristics and costs of ADM are between rubber mount and hydraulic mount. Nonlinear model with lumped mechanical and air elements for dynamic characteristic analysis of an ADM with a throttle orifice is proposed. A computer simulation for a typical ADM used in powertrain mounting system is performed, and the results are compared well with experimental data. The factors and laws that affected ADM dynamic characteristics, such as orifice diameter, orifice length, initial volume, excited amplitude and temperature are studied. And it is concluded that if the length of orifice is unchanged, decreasing the diameter of orifice will provide better damping effect. The modeling method and simulation results presented in this paper will contribute to research and development of ADM.