Abstract: In order to realize the high precision pointing observation of the five-hundred-meter aperture spherical radio telescope (FAST), the control accuracy of the feed cabin on the flexible foundation is systematically studied. The dynamic performance of the feed cabin is ensured through the measures such as lightweight and high rigidity structural design, joint simulation of motion and control, semi-physical simulation experiment and on-site testing. Through the secondary adjustment device composed of AB axis and Stewart, the large scale, high precision, high sampling rate measurement control technology is adopted to realize that the feed cabin can overcome the influence of high altitude wind disturbance, cable vibration and its own kinematic coupling in a large scale space of 100 meters, and locate the feed source at the instantaneous focus.