Abstract: The main structure of Five-hundred-meter Aperture Spherical radio Telescope（FAST）has been completed. Till now, more than 100 new pulsars have been detected by FAST during the commissioning and test observation stage, and the project passed the national review in January 2020. Being the largest and most sensitive single-dish radio telescope, FAST will enable scientists to jump-start many science cases. Meanwhile, FAST have several application goals described in this paper. For instance, in deep space exploration, FAST will improve the ability of space measurement and control to the edge of the Solar System. Moreover, FAST will increase the measurement accuracy of the time of arrival for the pulsar to 30 ns and develop the most accurate pulsar timing array, which will work for autonomous navigation. FAST could be the receiving system of the incoherent scattering radar, providing the ground-based observation with high resolution and efficiency. By carrying out microware survey to detect weak space signals, FAST might work for the Search for Extra Terrestrial Intelligence（SETI）and national security. After the formal operation, FAST will make significant contributions to these important application goals.