China's Eye of the Sky is also called FAST for short, so what is its significance and function? First of all, there is no China in China, because China's astronomy, like other disciplines, developed later than other countries. Therefore, when there are no pastoral areas in China, our country can only choose to cooperate with foreign countries on many issues of studying the astronomical universe. That is, if we want to study some problems in the universe, we can only seek help from other countries. Borrow their binoculars. This has led to some marginal problems in China's astronomical research, caused the core problem of our country's study of the universe, and caused our astronomers to be unable to study the real core problem. Today, China's FAST will eventually be built, and a scientific research framework has been formed. We have completely got rid of foreigners and don't need to borrow their astronomical telescopes. Nowadays, the completion of astronomical telescope in China enables China to explore the mysteries of the universe with its own telescope in the sense of studying cosmic science. The function of FAST is mainly to observe neutral hydrogen lines and other centimeter-band spectral lines. In this way, we can explore the structure of interstellar matter from the origin of the universe, look for weak pulsars and other weak radio sources, provide a high-sensitivity and high-resolution ground tracking and remote control base for our own exploration plan, and develop into a new model of giant radio telescope.