Abstract: The development of Terahertz technology and research progress are briefly summarized.The unique properties of Terahertz wave,such as low energy,high penetrability,dactylogram,broadband,transient and coherent are generally introduced.Existing and emerging applications of terahertz technology in imaging,radar,communication,biomedicine,antiterrorism and security detection,spaceflight,astronomy and geography are illustrated.An emphasis is put on the field of radar detection and communication system.For high ran...