The finite element model of a large-type vertical motor was established based on virtual prototype and finite element simulation system, in which bearing characteristics of the motor structure and effects of electromechanical coupling & electromagnetism coupling were considered. The laws of motor vibration distortion distributing and structure destroy were analyzed, the main destroy form and location of the motor structure are confirmed according to finite element analyses. Research results showed that imbalanced effect of unilateral magnetic force is an important vibrating fountain. The correlation structures or the whole motor could be caused to vibrate intensively while the frequency of the unilateral magnetic force produced by the main magnetic field is close or same to a natural frequency of the motor. At the same time, the joined stiffness of foot bolts affects the natural frequencies of the motor clearly, with the number of foot bolts increasing, the natural frequencies of large-type motor are increasing, while foot bolts invalidating, the natural frequencies would fall, and this could cause the motor to vibrate tempestuously or resonate.