Abstract: The first feed-support system, which is one of the key techniques of FAST, is introduced in this paper. Systemic experimental research with the scaled model, which is one of thirtieth of actual structures, is made. In the experiment, the position deflection of the feed-car was analyzed when the feed-car ran along the part of a circle. Furthermore, the equivalent rigidity of the system was measured and the position deflection of the feed-car resulting from wind was computed. The research results confirmed that the first feed-support system meets the required position control precision. Also, the results are very helpful to the precise position control of the large span cable structures.