The invention relates to a method for preparing wheat 
bran dietary fiber by utilizing 
ultrasound-assisted 
enzymatic hydrolysis, and in particularly belongs to the technical field of the agricultural and sideline product development, the 
functional food additive and the nutritional heath caring. The invention is characterized in that the invention adopts wheat 
bran as the 
raw material, and the wheat 
bran dietary fiber preparation is realized through utilizing the 
ultrasound treatment, and removing 
starch and 
protein by enzymatic method, and then the preparation of fine 
dietary fiber with different grain size is realized by crumbling with a grinder. The invention realizes the effective value increment and the utilization of the wheat bran, the prepared functional dietary 
fiber has important 
physiological function, and thereby can realize the functions of preventing 
constipation, colon 
cancer, intestina diverticulum, hemorrhoid and 
varicose veins of the lower extremities; the 
serum cholesterol is lowered, and the 
heart disease caused by coronary sclerosis can be prevented; the sensitivity of the 
peripheral nerve tissue to the 
insulin is improved, and the 
blood sugar level of the diabetes patient can be regulated, the invention is very useful for 
human health, and the economic benefit as well as the social benefit are greatly increased.