Vibration results from situation when the inherent frequency close to the external exciting force during the operation of the motor, so accurate and effective calculation of the natural frequency of the motor has an important significance to damping noise. By numerical simulation model and the ANSYS finite element modal, the inherent frequencies were got of the motor and comparison results verify the effectiveness of the motor model. The effect of the modulus of elasticity of the softening layer between the motor and the ground to the inherent frequency was researched intensively, and puts forward related suggestions.