Abstract: In practical applications, most servo positioners adopt a structure in which the main shaft of the rotary platform is directly connected to the reducer. This connection subjects the reducer to a large overturning moment. Long-term operation under unidirectional eccentric load tends to cause severe and uneven wear, resulting in degraded equipment accuracy and shortened service life. To address the above problems, this paper presents an optimal design for the servo positioner structure. Firstly, the mechanical structure is improved so that the reducer only bears the rotational torque and avoids the effect of overturning moment. Secondly, a servo motor is used as the driving source, and the dynamic response performance and repetitive positioning accuracy of the system are improved by reasonably matching the load inertia with the motor inertia.