Abstract: In practical applications, most servo positioners adopt a direct connection between the rotary platform spindle and the reducer. Such a configuration subjects the reducer to considerable overturning moment. Under long-term unidirectional eccentric load, the reducer suffers from severe and uneven wear, which consequently degrades the positioning accuracy and shortens the service life of the servo positioner. Aiming at the problems arising from the above connection mode, this paper focuses on the structural design and research of the servo positioner. Firstly, the mechanical structure is optimized so that the reducer only bears the driving torque and is free from the action of overturning moment.Secondly, a servo motor is employed to provide driving power, and the load inertia is matched with the motor inertia via theoretical calculation, so as to enhance the response speed and repetitive positioning accuracy of the positioner.