Abstract: To address the issues of easy aging, hardening and flavor loss of Baiji Bread, potato starch-whey protein isolate (PS-WPI) complex was used to replace wheat flour in different proportions (0%, 5%, 10%, 15%, 20%) to make Baiji Bread, and its effects on product quality, flavor and in vitro digestibility were investigated. The results of sensory evaluation showed that the addition of PS-WPI complex could effectively improve the sensory quality of Baiji Bread. The morphology, taste and aroma of Baiji Bread samples in the PS-WPI-15% group were the best, and the crumb structure and crust color were more uniform. The sensory score increased with the increase of the substitution ratio of PS-WPI complex, and the sensory evaluation decreased slightly when it was further increased to 20%. The water retention results showed that the PS-WPI complex could effectively slow down the mass loss rate of Baiji Bread especially when the substitution ratio was 15%, the effect was the best, indicating that the water retention capacity of Baiji Bread was enhanced; texture profile analysis showed that with the increase of the proportion of the complex, the hardness, gumminess and chewiness of Baiji Bread decreased, and the sample showed a softer texture.A total of 27 volatile compounds were identified by GC-IMS analysis, mainly aldehydes, esters, ketones and alcohols. The addition of PS-WPI complex increased the relative content of esters with fruity and baked flavors, while the relative content of aldehydes and ketones with grassy and fatty flavors decreased, which made the overall flavor more coordinated. By calculating the relative odor activity value (ROAV), the key volatile flavor compounds of each group of Baiji Bread samples were determined, including heptanal, (E, E)-2,4-hexadienal, ethyl hexanoate, ethyl isobutyrate, 1-octen-3-one, 2-furanmethanol, linalool, 2-methylpropionic acid and 2-acetylpyridine. In vitro digestion experiments showed that the content of resistant starch (RS) increased with the increase of the substitution ratio of the complex, and the content of resistant starch in the PS:WPI-15% group reached the highest (27.00%), which effectively reduced the content of rapidly digestible starch (RDS) (49.80%). This experiment showed that replacing wheat flour with 15% PS-WPI complex could improve its in vitro digestibility while optimizing product texture and improving flavor coordination, which provided theoretical basis and technical reference for the formulation improvement of related flour food.