Porous starch was prepared by combined-enzyme method (sqaccharaseandα-amylase) by using proso millet starch as rawmaterial and oil absorption rate as index. On the basis of single factor experiment， the process parameters for the preparation of proso millet porous starch was optimized by Box-Benhnken response surface methodology. The structure of the original starch and proso millet porous starch were characterized. The results indicated that the optimal process parameters for preparing proso millet porous starch by combined-enzyme method were combined-enzyme addition of 1.2%， enzymatic reaction temperature of 56 ℃， enzymatic reaction time of 14 h， enzymaticreaction pH of 4.5， combined-enzyme ratio of 1 ∶ 4. Under the optimized process condition， oil absorption rate of proso millet porous starch was (174.00±2.00)%. The surface of porous starch granules had uneven distribution of holes， circular depressions， and the internal structure was hollow by SEM. The particle size distribution test indicated that the particle size decreased slightly and the distribution uniformity of starch particles increased. The enzyme hydrolysis did not change the A-type crystal structure and basic chemical structure of proso millet starch by FT-IR and X-ray diffraction. The relative crystallinity and infrared absorption peak of proso millet starch were significantly increased. The inner order degree of starch granules was improved. Low temperature nitrogen adsorption results showed that the enzymatic digestion of the complex enzyme increased the specific surface area of proso millet starch from 13.9 m2/g to 29.42 m2/g， the pore size from 4.143 nm to 6.637 nm and the pore volume from 14.81×10-3 cm3/g to 25.05×10-3 cm3/g. The pasting property test indicated that the peak viscosity and breakdown of porous starch were reduced. This study can provide reference frame for the development and application of porous starch and the deep processing of proso millet.