Abstract:National major scientific and technological infrastructure is a crucial pillar of national innovation, fulfilling multiple missions such as advancing scientific research, supporting engineering practice, and enhancing public scientific literacy. This study takes the Five-hundred-meter Aperture Spherical Radio Telescope (FAST), known as the "FAST project," as an example case to explore the practices and innovations in scientific communication within such national infrastructure. As the world's largest singledish radio telescope, the FAST project employs various methods, including exhibition halls, open days, popular science reports, educational programs, and all-media communication, particularly targeting rural and economically disadvantaged areas like Guizhou Province. These efforts provide effective pathways to bridge the gap in scientific education between urban and rural areas, thereby improving national scientific literacy. This study introduces and summarizes the "Three Exits and Three Entries" model for scientific communication:researchers stepping out of the laboratory, scientific achievements moving beyond academic publications, and scientific culture transcending traditional communication methods. Simultaneously, this model emphasizes bringing researchers into enterprises and schools, integrating scientific achievements into national and public life, and extending scientific culture to remote villages. The successful application of this model offers valuable insights for the scientific communication strategies of other major national scientific and technological infrastructures. Moreover, it supports the conversion of scientific research outcomes into drives of social and economic development, advancing national science and technology strategies and enhancing China's global influence in science and technology culture.