Abstract: The sweet potato residue was got by simulating the extraction process of sweet potato starch.Effects of the addition amounts of various enzymes on the extraction rate of dietary fiber were studied by single-factor and orthogonal experiments,and the enzymatic hydrolysis conditions of glucoamylase were optimized by orthogonal experiment.Results showed that the optimal addition amounts of various enzymes were α-amylase 1.4 mL/g,trypsin 0.5 mL/g and glucoamylase 5.0 mL/g,and the glucoamylase was identified as the main enzyme.The optimal conditions for glucoamylase hydrolysis were 60 ℃,40 min and pH 4.5.The extraction rates of total dietary fiber and soluble dietary fiber under the optimal conditions were 81.6% and 25.7%,respectively.The expansion and the water holding capacity of dietary fiber reached 3.42 mL/g and 665%,respectively.