Book excerpt: Agri-product such as grains, fruits and vegetables play a very important role in people's daily life. The agri-product quality directly affects human life and health. Agri-product quality refers to the quality characteristics acceptable to consumers, which mainly includes external factors such as size, shape, color, defect and texture, and internal factors such as physical properties, chemical composition and tissue diseases. Generally speaking, variety, climate, soil, cultivation techniques, diseases and pests are all factors that affect the agri-product quality. Traditional methods for agri-product quality evaluation are time-consuming, complex, and expensive. With the continuous development of modern science and technology, rapid and nondestructive detection technologies are applied to evaluate the quality of agri-product. These technologies could obtain the optical, acoustics and electrical properties of a specific substance and then reveal the appearance and internal quality of the agri-product. Furthermore, the trend today is that consumers have become more exigent for information about the products they purchase, which makes the nondestructive detection technology has more important application value in the field of agri-product quality evaluation.