In recent years, food adulteration incidents have occurred frequently, which poses a huge threat to food safety. This problem has become the focus of people’s attention and hotspots for discussion. Therefore, the realization of fast, accurate and non-destructive testing of food adulteration is of great significance for ensuring food quality and safety. With the continuous emergence of new food raw materials, additives and food processing technologies, food adulteration is being technical, invisible and diversified, bringing more severe challenges to adulterate identification. At present, there have been some new methods for effective food adulteration detection, including high-performance liquid chromatography, stable carbon isotope ratio method, etc. However, due to the complex pretreatment of the sample and the high technical requirements for the detection instrument operation, these methods’ application has been limited. Hence, A new type of non-destructive technology with high sensitivity and fingerprint characteristics is necessarily required. Terahertz (THz) spectrum refers to electromagnetic waves with a frequency from 0.1 to 10 THz, between microwaves and infrared waves, which has the advantages of fingerprint characteristics, coherence, security, etc. Since the skeleton vibration, dipole rotation, and vibration transition of most macromolecules in organic substances and the weak interaction between them can be reflected in the THz spectrum. The THz technology possesses great potential in food adulteration detection. This paper elaborated THz spectroscopy technology’s detection mechanism and reviewed the latest research progress of food adulteration detection by THz spectroscopy, including genetically modified foods identification, food geographical origin traceability, adulteration detection of dairy products, honey and other foods. Then, THz spectrum technology’s existing application problems in food adulteration detection were analyzed, such as moisture influence, scattering influence, etc. At last, the applications of the THz spectrum technology in the food adulteration detection field prospected, such as the development of low-cost THz sources and detectors to promote the popularization and application of terahertz technology, the use of machine learning algorithms for THz spectrum modeling and analysis to improve model accuracy and analysis speed, combination with other modern detection technologies to achieve advantageous complementarities, etc. This paper is expected to provide reference and guidance THz spectrum technology research in food adulteration detection.