Abstract: In this study, maltodextrin(MD)was produced from waxy rice starch by enzymatic hydrolysis with thermostable α-amylase.The final viscosity and dextrose equivalent(DE)were chosen as response values to optimize the experimental conditions to prepare low DE maltodextrin.The effects of various factors, including reaction time, temperature, starch concentration, and enzyme dosage, on the final viscosity and DE were studied.Orthogonal test design was used to optimize experimental conditions of produced maltodextrin.The structure and properties of the maltodextrin were compared with those of waxy rice flour and waxy rice starch.The results showed that the optimal processing conditions to prepare low DE maltodextrin(75 g waxy rice starch as substrate)were as follows: reaction time of 7.5 min, reaction temperature of 95 ℃, the starch concentration of 25%, enzyme dosage of 50 μL.The DE of maltodextrin prepared under these conditions was 1.6 and the final viscosity of maltodextrin was up to 104.96 mPa·s.Compared with waxy rice flour and waxy rice starch, maltodextrin had no obvious endothermic peak.The weight loss rate of maltodextrin was lower than that of waxy rice flour and waxy rice starch, so its thermal stability was improved.The FT-IR spectra showed that the ratio of intensity at 1 047 cm^-1 to that at 1 022 cm^-1(IR_{1 047/1 022})of maltodextrin was higher than those of waxy rice flour and waxy rice starch, as well, the ratio decreased with the increase of DE.The crystallization peak disappeared and the spectrum appeared diffuse, showing an amorphous structure of maltodextrin.