At present, in the industrial production process of corn starch sugar, there are some problems in the saccharification reaction stage, such as low initial starch milk concentration, long reaction time, poor enzymatic hydrolysis effect, low yield of final product, and more miscellaneous sugar components. Aiming at the above phenomena, the optimal saccharification conditions were obtained by orthogonal design with the parameters of the saccharification reaction stage, such as temperature, pH value, and the amount of enzyme added by using starch milk with 40% concentration as raw material. At the same time, the effect of DE value of glycosylated substrate on the glycosylation reaction and the composition of glycosylated products was analyzed. The results showed that the main factors affecting the glycosylation reaction were pH > enzyme amount > substrate DE value. The optimum conditions for the reaction of glycosylase were temperature 60 ℃, pH 4.5, enzyme dosage 200 U/g and substrate DE 15. Under this condition, the viscosity of the saccharification solution was moderate, which was more conducive to the enzymolysis reaction. The DE value of the final product could reach 95% and the glucose content (DX value) could reach 96.86%. Meanwhile, the content of other components was only 1.30%. The conclusion of this study can provide theoretical reference for the industrial production of corn starch sugar to improve product yield and reduce cost.