Abstract: In order to improve the physiological functions of dietary fiber from sweet potato residue, insoluble dietary fiber (IDF) was prepared from sweet potato residue for physical and chemical properties ultra-high pressure modification with uniform test method. And insoluble dietary fiber was characterised by the methods of SEM, HPCE, FT-IR, XRD, BET and particle size. The conclusion shows that the pressure (X1), processing time (X2) and temperature (X3) had the significant influences on glucose regulation, blood fat regulation and the ability of removing exogenous harmful substances in modified IDF. The optimum processing conditions were that the glucose regulation and blood fat regulation capacity were pressure of 600 MPa, processing time of 15 min and temperature of 60℃; The ability of removing exogenous harmful substances were pressure of 100 MPa, processing time of 10 min and temperature of 42℃. The physicochemical property shows that the microstructure of sweet potato residue IDF modified by the ultra-high pressure was loose, smooth, porous with honeycomb-shaped and massive structure. Either modification didn't affect the monosaccharide compositions, but the contents of monosaccharide changed a little. Meanwhile, crystal and particle size of modified IDF reduced, the specific surface area increased. The characteristic absorption peaks enhanced and a red shift or blue shift appeared, and a number of new absorption peaks occured. The research can provide a reference for functional modifications and utilization of dietary fiber from sweet potato residue.