Abstract: To develop a low-digestible bakery product that met the market's demand for healthy products, the preparation conditions for extruded yam starch-gallic acid complex (EYS-GA) were optimized using single-factor experiments and response surface methodology. EYS-GA, with a high content of resistant starch, was used to replace varying amounts of wheat flour in cake production. The impact of different EYS-GA additions on the gelatinization characteristics of the mixed flour, as well as on the texture properties, moisture distribution, and in vitro digestion characteristics of the cakes, was investigated. The optimal preparation conditions for EYS-GA were found to be an extrusion temperature of 91 °C, a moisture content of 30%, and a screw speed of 180 r/min. Under these conditions, the resistant starch content in the prepared EYS-GA reached 51.34%. Compared to the control group without EYS-GA, addition of 20% EYS-GA to wheat flour resulted in a 17.76%, 12.44%, 16.82%, and 11.25% reduction in peak viscosity, disintegration value, final viscosity, and setback value, respectively. The hardness and chewiness of the resulting cakes increased by 110.00% and 90.36%, respectively. The addition of EYS-GA enhanced the cakes' resistance to digestion and improved the overall cake quality.