Abstract: In this study, to investigate the effect of starch granule size on the physicochemical properties of wheat starch-lauric acid complexes, wheat starch granules were divided into three fractions by Stokes sedimentation method.Based on the data analyzed by alaser particle size analyzer, the average equivalent granule diameters of small granule wheat starch, medium granule wheat starch, and large granule wheat starch were 5.81 μm, 11.09 μm, and 24.21 μm, respectively. In the research system, the wheat starch was set as the research object, medium and long chain fatty acid-lauric acid was set as lipid ligand, the effects of granule sizes on complexing index, thermal properties, crystal structure, and short range order of the wheat starch-lauric acid complexes were determined.Then, the digestive kinetics model was established by in vitro simulation to study their influences on the digestibility of the complexes. The results showed that the larger the granule size was, the higher degree of complexing with lauric acid was.The complex with larger complexing index showed a higher enthalpy (ΔH). Compared with the native starch, the phase transition temperature (T₀), crystal crystallinity and short-range ordered molecular structure of the wheat starch-lauric acid complexes increased significantly, and the increasing range of the complexes gradually increased with the increase of granule size. Related digestibility experiments showed that granule size affected the digestion dynamics of the wheat starch-lauric acid complexes. Compared with the native starch, the digestion rate of large granule wheat starch-lauric acid complexes decreased. In detail, the k value of the native starch was 0.023 0 min^-1, and the k value of the complex was 0.018 9 min^-1.The content of rapidly digestible starch decreased, and the content of resistant starch increased. There was significant difference in the digestion rate of starch-lauric acid complexes in medium granule wheat starch. The digestion rate of small granule wheat starch-lauric acid complexes increased. In detail, the k value of the native starch was 0.029 6 min^-1, and the k value of the complex was 0.033 2 min^-1, accompanied with an increase in the content of rapidly digestible starch.