(1) Allulose is the differential isomer corresponding to the third position carbon of D-fructose. It has the special function of regulating blood sugar and is the most potential substitute of sucrose. D-allulose is difficult to digest and provides little energy for vital activities, so it is a very useful low-calorie sweetener. (2) In the field of medicine and health, D-allulose can inhibit the fatty liver enzyme and intestinal α-glycosidase, so as to reduce the accumulation of body fat and inhibit the rise of blood sugar concentration. (3) In the field of food application, D-allulose has the advantages of high sweetness, good solubility, low calorie, hypoglycemic reaction, etc. and is considered to be one of the most ideal sucrose substitutes. Adding D-allulose into the food can not only improve its gelation, but also improve its favor through Maillard reaction with food protein.