Spectral detection has a wide range of applications in substance identification, materials science, biochemical and pharmaceutical research. Terahertz, as a section of electromagnetic spectrum locating between the millimeter wave and the infrared at frequency, plays an important role in the field of spectral detection in recent years due to its unique spectral properties. Compared with the spectral detection of other frequency bands, the characteristic absorption of the terahertz spectrum by polar molecules and the strong coherence of the terahertz wave make the terahertz spectral detection directly obtain the physical and chemical properties of the material. This article first introduces the principle of terahertz technology, then introduces the characteristics, development history and current status of terahertz spectroscopy technology, and finally gives the development trend of terahertz spectroscopy technology.