Extrusion processing technology is one of an important modern food processing technology，it has been widely used in grain food processing．Many studies have shown that extrusion processing has brought significant physical and chemical changes in the cereal starch which affects the quality of products. The different parameters in extrusion process could produce different effects on the change of starch．The effects of extrusion processing on the physical and chemical properties of grain starch was reviewed from the aspects of starch composition, molecular structure，particle characteristics，crystallization characteristics，gelatinization properties and hydration characteristics，in order to provide an important basis for the processing of cereal food and the application of starch modification．