Terahertz non-destructive testing technology is a more comprehensive technology, which is an important part of terahertz technology application, it involves different areas such as physics, material science, semiconductor technology, optoelectronics and super-conduction electronics. The imaging principle based on terahertz time-domain spectroscopy is introduced. And the principle and applications of typical terahertz non-destructive testing technology are introduced. The works of scholars in the area at home and abroad are introduces too.