Abstract: Recently, driving force from the development of radio astronomy and atmospheric science makes THz time-domain spectroscopy technology develop rapidly, widely used in the field of remote sensing. Related techniques and application are presented here, including earth observing system and radio astronomy. Close relation between THz remote sensing and other subjects is highlighted, showing great foreground of application. America, Europe and Japan started earlier in the field of THz remote sensing, owning several advanced techniques and equipments; China started later, whose techniques fall behind the international advanced level.