There has been a series of significant advances and applications in terahertz (THz) technologies which processes perspectivity, safety and spectroscopic fingerprinting ability. The unique properties of THz waves make them become tools for non-destructive detection and application in the fields of defense, industry, semiconductor, communication, biological medicine, pharmaceutical, agro-products, food and etc. Firstly, the principle and feature of THz spectroscopy and imaging techniques were introduced. Then, the non-metallic material characterization and defect inspection in foam and fiber composites were stated. The recent application of THz in agro-products and food was introduced mainly. Finally, the technology difficulties and issues of the THz technologies were analyzed, and their development prospects in the non-destructive detection field were presented.