Adlay seed (Coix lacrymajobi L.) is the mature seed kernel of adlay， a gramineous plant， with a protein content of 12.2% to 16.7%， rich in glutamine， leucine and proline， and easily absorbed by the body. Despite its nutritional balance and healing properties， adlay seed remains an underutilized grain due to its difficult-to-cook characteristics. Extrusion technology integrates mixing， stirring， crushing， heating， sterilization， puffing and forming into one， resulting in a product with not only a higher degree of pasting but also a short production cycle and low cost， which facilitates the consumption of adlay seed and indirectly promotes the economic growth of the adlay seed consumption industry. Some studies have shown that changes in the secondary， tertiary and quaternary structure of proteins depend on high temp-induced cross-link aggregation and high shear-induced mechanical unfolding， so extrusion treatments could have an impact on the structure and properties of proteins. For example， extrusion treatment could induce partial breakage of the hydrogen and disulfide bonds between protein molecules， causing denaturation of proteins， which in turn has an impact on solubility， emulsification and digestibility of proteins， providing new ideas for obtaining a wide range of adlay seed protein products. However， most of the research on the extrusion processing of adlay seed has focused on the effect of extrusion treatment on the starch properties of different varieties of adlay seed， while the extrusion processing of adlay seed protein is less. In addition， in order to enrich and develop the research system of adlay seed protein modification， it is necessary to further explore the influence of extrusion treatment on the structure and properties of adlay seed protein components. Therefore， in this study， defatted adlay seed powder was used as the raw material for extrusion and the Osborne classification method was used to separate and extract albumin， globulin， prolamin and glutenin to investigate the effects of extrusion treatment on the structural and functional properties of the four protein fractions. The results showed that the particle size of all four protein fractions decreased significantly after extrusion， and the particle size curves of globulin， prolamin and glutenin showed a multi-peaked distribution. After extrusion， the free sulfhydryl content of the albumin， globulin and glutenin decreased by 72.37%， 40.64% and 51.71%， respectively. And the maximum fluorescence absorption wavelength of these protein fractions was blue-shifted， and the subunit types and molecular weight were also significantly reduced， but there was no significant change in the prolamin. With the exception of globulin， the content of ordered structures， i.e.， α-helix and β-sheet， in the secondary structure of all three protein fractions was significantly reduced after extrusion(P < 0.05). The water- and oil-holding properties of the albumin， globulin and glutenin were significantly increased (P < 0.05). In conclusion， the structural properties of albumin， globulin and glutenin were significantly changed after extrusion， but the prolamin had higher structural stability and resistance to thermal shear. The results could provide theoretical support for the industrial preparation of adlay seed protein fractions and their application in a variety of food formulations.