In modern industrial equipment, particularly when using in the high precision conditions, the servo motor technology is developed into high torque density, as a result, the rotation speed may be up to more than 3000 rpm. With the improvement of rotation speed, power density of servo motor is also greatly improved, that means whether a servo motor needs to be matched with a reducer gearbox is mainly determined by the application need and the cost. In following application conditions, a servo planetary reducer gearbox is needed.