Abstract: Wheat bran feruloylated arabinoxylan significantly inhibits starch digestibility, and this inhibitory effect is correlated with the proportion of free ferulic acid. To clarify the regulatory role of free ferulic acid in starch digestion behavior, this study employed quartz crystal microbalance with dissipation monitoring (QCM-D) and isothermal titration calorimetry (ITC) to investigate the complexation behavior between ferulic acid and wheat starch during co-gelatinization and its influence on starch digestibility. The results indicated that compared with the pure starch control group, ferulic acid significantly reduced the final hydrolysis extent and hydrolysis rate constant of wheat starch (P<0.05). Iodine binding capacity and complex index analyses revealed that ferulic acid weakened the iodine-binding ability of starch, indicating the formation of a starch-ferulic acid complex. Further multi-scale structural characterization demonstrated that ferulic acid disrupted the long- and short-range ordered structures of starch during retrogradation. QCM-D results confirmed that the apparent adsorbed mass of ferulic acid on the starch surface reached 817.09 ng/cm². ITC analysis showed that the adsorption of ferulic acid onto wheat starch was a spontaneous exothermic process (ΔH<0, ΔS>0), driven primarily by enthalpy-dominated hydrogen bonding (ΔG=-3.15×10⁴ J/mol). In summary, during co-gelatinization, ferulic acid interacts with wheat starch mainly through hydrogen bonding, which reduces the crystalline order of gelatinized starch during retrogradation, decreases amylase accessibility, and thereby slows the digestion rate. These findings provide new insights for the development of whole wheat flour products.