China is a big agricultural country, and ensuring food security is a strategic need for national development. The application and development of agricultural product detection are crucial for quality control and avoiding safety accidents caused by quality problems. Terahertz (THz) wave is located in the gap between the microwave and infrared regions of the electromagnetic spectrum, the frequency of which is higher than a microwave but lower than infrared and has low photon energy, good penetration, as well as can be used to characterize the molecular structure. The detection technology based on terahertz has been applied in bio-medicine, safety inspection and other fields and has been proved to be a reliable detection method. For agricultural products, the terahertz wave's unique untouched and label-free capability provides a method for composition analysis and quality control. Based on its penetration and non-destructive, the terahertz spectrum is also used to detect the internal ingredients without damaging agricultural products' surface and outer packaging. Compared with other spectral detection technologies(ultrasonic, X-ray, infrared, etc.), terahertz wave is in a wide frequency range with a good characteristic spectrum and can be used for rapid non-destructive detection. In recent years, with the development of THz sources, THz detectors, THz spectroscopy and imaging technology, the application of terahertz in agricultural products detection has further development. Through collecting and sorting out recent relevant information, this paper reviewed the new progress of terahertz technology in agricultural product detection, summarized the limitation of terahertz application, and discussed the future study direction of terahertz spectrum and imaging——improving sensitivity and accelerating detection speed are research focuses for industrialization application of terahertz detection technology. The metamaterial-based sensors are applied in the terahertz detection system to improve the detection sensitivity, which is of great significance to detecting pesticides, mycotoxins and other pollutants that harm the safety of agricultural products. The terahertz computational imaging technology based on single-pixel imaging and compressed sensing algorithm is a feasible solution to accelerate the detection speed in the rapid imaging detection of agricultural products. These researches provide direction for the subsequent development of terahertz technology and offer an important reference for the application promotion of agricultural products terahertz detection.