Terahertz wave lies between far-infrared and microwave in electromagnetic spectrum with frequency form 0.1 THz to10 THz. Terahertz is believed to be the master technology of electronics and information science, and to be the bridge between micro electronics and macro wavelength. THz has formed a worldwide research climax. This paper introduces the main characters of Terahertz wave, Terahertz time-domain spectroscopy technology and its application researches, especially detailed the researches in pesticide spectra.