With rice bran dietary fiber as raw materials,soluble dietary fiber was prepared through xylanase enzymatic modification to improve the quality of dietary fiber. Total dietary fiber,soluble and insoluble dietary fiber were obtained under optimal condition. Water holding capacity and oil holding capacity were significantly increased, while swelling capacity decreased after xylanase modification. Glucose adsorption capacity( GAC) of total dietary fibre( X-TDF),soluble dietary fibre( X-SDF) and X-IDF were 1. 28,1. 35 and 2. 11 times of that of rice bran dietary fibre( RBDF). Glucose dialysis retardation index( GDRI) of X-TDF and X-IDF were significantly enhanced,GDRI of insoluble dietary fibre( X-IDF) was reduced,however. Adsorption capacities of X-TDF and X-SDF for cholesterol were also increased. With observation of the ultrastructure using scanning electron microscopy( SEM),it was found that many cavities and cracks appeared after xylanase enzyme modification.