The Five-hundred-meter Aperture Spherical radio Telescope (FAST), which is the largest and most sensitive radio telescope in the world, has made some important achievements. Due to the rich research potential and technology requirement, a new generation of feed cabin is proposed to improve the observation zenith angle of the telescope close to the galactic centre and reduce the weight of the feed support system. Taking the workspace and cable force as optimized conditions, a dimension design method is put forward to ensure the force stability of the reconfigurable cable parallel robot. Finally, a set of optimized dimensional parameters are obtained which will greatly enhance the maximum observation zenith angle from 40° up to 50°. Based on the research of this article, we will conduct in-depth research and design in the future. We plan to update the feed cabin in the next 2–3 years, greatly improve the observation capacity of FAST, and may use this design for the future FAST array project.