Abstract: It was described the preparation and properties of high purity indigestible dextrin. The corn starch was acidhydrolyzed under 180℃ for 0.5h by adding 12% (V/W) HCl solution (1% W/W) firstly, and then mixed with 10 folds water (V/W) and enzymolyzed by amylase and glucoamylase. The hydrolysis was concentrated under vacuum and then precipitated with ethanol to be purified, the precipitation for 6 times was the production of indigestible dextrin and the yield was 40.32% and the purity was 95.30%. Analysis of molecular weight distribution and DSC-thermogram of high purity indigestible dextrin were studied, the results showed the high thermal stability and the heavy molecular weight was 8607 u, which provided some information for its application in all kinds of food.