Abstract: Wheat bran is the main source of dietary fiber that is one of seven nutrients in food. Besides, it is also beneficial for human health, such as high antioxidant, fat reduction, prevention of obesity, and constipation, etc.Soluble dietary fiber(SDF) shows a higher physiological activity than that of insoluble dietary fiber(IDF). Therefore, in the present work, wheat bran was treated with an acid-enzyme combination method to increase the content of soluble dietary fiber in wheat bran, and single factor and orthogonal experiment was conducted to determine the acid treatment (pH, temperature and extracting time) effect on the extraction yield of soluble dietary fiber from wheat bran.In addition, SDF and IDF was extracted from the processed dietary fiber (DF) and their physical and chemical properties, oxidation resistance and the analysis of structural characteristics were compared with that of the original wheat bran and DF.The results showed that the optimum acid treatment conditions were pH 2.0, temperature 100 ℃ and time 2.0 h, under these conditions, SDF extration rate was 21.39%. After enzyme-acid treatment, the content of SDF was significantly increased, and the water holding capacity, expansion capacity and oil holding capacity of DF, SDF and IDF were higher than those of original wheat bran. While the antioxidant capacity was in the order of DF> SDF> IDF> original wheat bran at the same mass concentration. The characteristic absorption peaks of modified DF, SDF and IDF were slightly different, and the intensities of absorption peaks were obviously different. The combined treatment of acid-enzyme could significantly increase the content of soluble dietary fiber in wheat bran, as well as improve the adsorption characteristics and antioxidant function characteristics of total dietary fiber. This study provided a theoretical reference for further processing and utilization of wheat bran by-products.