With the development of modern society, the demand of information is exploding, which results in the insufficiency of the low frequency spectrum. The frequency is expanding to terahertz frequency band (0.1 THz~10 THz). Nowadays, the terahertz communication technology has become one of the key trends of future large-capacity communication. Aiming at terahertz communication technology, we will introduce the characteristics and applied scenarios of terahertz communication. The development of core devices and the comparison of present communication system achievements at home and abroad, along with future development trends are illustrated in our article. Meanwhile, terahertz microwave photonics communication system, all-solid state terahertz mixer communication system and direct modulation terahertz communication system are also introduced and discussed as follows. Finally, we present the development tendency of terahertz communication technology and its future applied scenarios.