Ultrafine grinding is an advanced technology that can grind materials down to the micron or even nanometer level, with significant advantages of material savings, fast grinding speed, and uniform and fine powder particle size. Recently, it has gradually been applied in the pre-treatment of grain crops, which has positive significance for the production of food with good taste, a high nutritional material dissolution rate, and strong functionality. This review summarizes the classification, advantages, and disadvantages of 7 different types of ultrafine grinding technology. The effect of ultrafine grinding technology on the nutrients (protein, starch, fat, dietary fiber and phenolic compound) and specific physiological functions (regulating blood glucose, blood pressure, blood lipid, antioxidant, and reducing harmful substances) of grains were also discussed, for providing a theoretical basis for the future research and development of grain products.