Abstract: Excessive grain processing and dietary changes are important factors affecting the increasing incidence of chronic diseases such as diabetes. This article introduces the concept of glycemic index and the glycemic index value of some common grain and its products. Meanwhile the factors that affect the glycemic index of grain and its products mainly include food ingredients and physical and chemical properties and food processing and cooking methods. The development and promotion of healthy grain products and the establishment and improvement of relevant standards for glycemic index would be of great significance to reduce the risk of chronic diseases and improve national health.