In order to achieve high-accuracy trajectory tracking at feed end of Five-hundred meter Aperture Spherical radio Telescope (FAST) support system and to prevent the force over-limit of supporting cables, the pose distribution algorithms of target end by the star-frame of feed support system and A-B rotator were studied in the article. Firstly, according to the mechanism characteristic of the feed support system, combining the time-varying barycenter and the back illuminating strategy applied in feed cabin, a mechanical model of cable-driven parallel system which considers the time-varying barycenter of feed cabin and provided with back illuminating strategy was established. Secondly, in order to solve the motion coupling between the A-B rotator and the star-frame, two pose distribution algorithms of the feed support system were designed: the pose distribution algorithm which gives priority on ensuring the balanced cable force of six-cable and the pose distribution algorithm which gives priority on ensuring the positioning accuracy of the feed receiver. Finally the performance of above two algorithms on positioning accuracy of the feed receiver and the distribution of cable force were analyzed. And the results show that the former algorithm is able to balance the cable force on six-cable, however the error due to introduction of maximum 1.2° of the feed receiver has been beyond the scope of the specified accuracy of the project. The second algorithm makes cable force on six-cable fluctuate significantly, but the force was not over the limit or under virtual pull, which means such algorithm meets engineering requirements because it can ensure the pose of the feed receiver.