In order to study many physical processes and complex coupling relationships of many parameters existing in the permanent magnet AC servo precision drive system, the system should be analyzed by means of electromechanical Coupling vibration. From the global electromechanical coupling point of view, the electromechanical coupling analysis was carried out on the permanent magnet AC servo precision drive system, and this system was concluded to the three qualities-two shafts system. Then, the electromechanical coupling vibration mathematical and simulation models of this system are built up, and the dynamic processes of electromechanical coupling vibration are simulated which are caused by current regulator parameters, damping, harmonic disturbance, gap, load disturbance, and so on. Finally, the simulation model is validated by the experimental study. This analysis is important to improve the dynamic performance of this system.