The developments of Terahertz (THz) spectroscopy and imaging technology in recent years are reviewed,including THz time-domain spectroscopy,time-resolved THz spectroscopy,THz emission spectroscopy,time-domain raster scan imaging,real-time imaging,tomographic imaging,continuous-wave imaging,and near-field imaging. Fundamental principles involved in THz spectroscopy and imaging techniques are introduced. Potential applications of THz technology,such as homeland security,biological research,materials research,non-destructive evaluation are discussed.