As an inherent nonlinear device, an analysis method of a balanced armature receiver (BAR) considering the nonlinearity, especial the nonlinear magnetic characteristics are important. From literature survey, the finite element method (FEM) could be considered as the most accurate analysis method. Thus, a mass of simulations with 3D FEM analyses are proposed in this paper to analyze the nonlinear characteristics of magnetic circuit in a BAR. The back-EMF can be calculated based on the flux passing through the armature, and the total force is generated based on the flux density in the air gap. It is should be mentioned that, as the flux density in the air gap and the flux passing through the armature changes according to both of the armature vibration displacement and the current in the coil, the back-EMF and the total force can be processed as functions in terms of the displacement and current. Therefore, the nonlinear magnetic characteristics can be obtained: the inductance and speedance can be acquired from the back-EMF, and the cogging force and the force factor can be acquired from the total force.The cogging force is considered as the magnetic stiffness, which acts as negative mechanical stiffness. The modal analysis is implemented with the reduced stiffness of the vibration system by using 3D FE static mechanical analysis. To verify the effects of nonlinear magnetic characteristics, the vibration displacement on the SDP around the area connected with pin should be measured in frequency domain. To eliminate the stiffness effect produced by the sealed air in the back volume and front volume in the BAR, samples with holes punched on both of the upper and lower cover are manufactured. The modeling of simulation and the simulated vibration displacement are followed the measurement, and verified experimentally.