Abstract: Using medium temperature type-amylase on potato starch hydrolysis,the DE value of potato starch hydrolysate was the evaluation index. Based on single-factor experiments of the effect of the p H,enzymolysis temperature and enzymolysis time, the optimum condition of potato starch enzymolysis was determined by response surface methodology. The results showed that the optimum conditions were as follows :p H7.90,enzymolysis temperature 62 ℃,enzymolysis time 60 min,under the optimum conditions,the enzymolysis of potato starch DE value was 57.93%.