The motor of motorized spindle is AC asynchronous induction motor, so it is used in high-speed machining machine tool. When starting, it needs to speed up rapidly from static state to tens of thousands or even hundreds of thousands of revolutions per minute. The starting torque is large, so the starting current should exceed the rated current of ordinary motor by 5 ~ 7 times. There are two driving methods: frequency converter drive and vector control driver. The driving control characteristic of the inverter is constant torque drive, and the output power is proportional to the torque. The latest frequency converter of the machine tool adopts advanced transistor skills, which can complete the stepless speed change of the spindle. The driving control of vector control driver is constant torque drive at low speed end and constant power drive at medium and high speed end.