Abstract:In this study,different proportions of whole oat flour,chickpea flour,and tartary buckwheat tea flour were added to rice flour and millet flour.After extrusion cooking,multigrain rice and millet with different raw material ratios were prepared,and the nutritional composition and in vitro digestion characteristics of multigrain rice and millet after extrusion cooking were investigated.The content of nutritional composition and starch nutrient fragments,including rapidly digestible starch （RDS）,slowly digestible starch （SDS）,and resistant starch （RS）,starch hydrolysis kinetics curve,and expected glycemic index （eGI） were mainly measured.The correlation analysis between the content of nutrient composition and nutrient fragments of multigrain rice and millet and the eGI value was conducted.The results showed that the protein content,fat content,and ash content of multigrain rice and millet after extrusion cooking increased significantly,and the fat content increased from 0.87% to 5.01%.The protein content increased from 8.74% to 9.89%.The RS content of multigrain rice and millet after extrusion cooking increased,and the RDS content,as well as starch digestibility and hydrolysis rate decreased.The addition of 50% whole oat flour had the greatest effect on multigrain rice and millet after extrusion cooking.Specifically,RS content increased by 195.46%,and RDS content decreased by 29.68%.The eGI of multigrain rice and millet after extrusion cooking significantly decreased,among which the eGI value of multigrain rice and millet after extrusion cooking with 50% whole oat flour decreased by 26.34%.The content of RS in multigrain rice and millet was negatively correlated with the eGI value （p<0.05）.