The motorized spindle is composed of a casing less motor, a spindle, a bearing, a spindle unit housing, a drive module, a cooling device, etc. The rotor of the motor is made into a whole with the main shaft by pressing, and the main shaft is supported by the front and rear bearings. The stator of the motor is placed in the housing of the spindle unit through a cooling sleeve to customize the spindle. The speed change of the spindle is controlled by the spindle drive module, and the temperature rise in the spindle unit is restricted by the cooling device. The rear end of the spindle is equipped with speed and angle measuring displacement sensors, and the inner cone hole and end face of the front end are used for installing tools.