This paper establishes the finite element method (FEM) model of a practical silicon beam resonator attached to a E-type round diaphragm, which is used for measuring the acceleration, in details, based on sensing mechanism of a novel resonant silicon accelerometer. The relationship between the basic natural frequency of the beam resonator and the measured acceleration is calculated, analyzed and investigated by making use of the above FEM model. Some important qualitative and quantitative results on the natural frequency-acceleration relationship of the above bema resonator and the microsensor are obtained. Finally, based on the differential output scheme, a set of appropriate parameters of the above sensing structure is determined, for measuring the acceleration within (-100, +100)m/s2. The simulation result shows that the differential frequency output is within (-8833, 8910) Hz and reference zero frequency is 126914 Hz for zero acceleration, corresponding to the determined parameters of the above sensing structure.