Abstract: Terahertz (THz) spectroscopy and imaging, as the focus of THz science and technology, can be applied in many fields, such as biology, physics, chemistry, safety check, aerospace, etc. And now they are becoming international attractive field especially in recent years. Firstly, the THz time domain spectroscopy, time resolved THz spectroscopy and THz supercontinuum technology were discussed briefly. Results for characteristic identification of explosives and research on dynamics of ultra-fast charge carrier by using different THz spectroscopy were presented. Meanwhile, the THz time domain scan imaging, real time focal plane imaging, continuous wave imaging, and passive THz imaging technologies were introduced respectively. In application study, research on sunflower seeds by using THz time domain scan imaging technology, plastic cap gun covered by canvas using real time focal plane imaging technology, aerospace foam and pistol model by using continuous wave imaging technology, human body by using passive THz imaging technology were all presented correspondingly.