Middle-temperature-amylase is extracted from fermented deeply Bacillus subtilis.It can hydrolyze starch and hepatin,dissolve internal Alpha-1,4 glucose glycosidic linkage,produce short-chain dextrine and oligosaccharide to reduce viscosity of gelatineous starch rapidly.This enzyme can be used in beer brewing,alcohol production,monosodium glutamate, starch sugar,feed,liquefication of fermentation business,fiber,printing and dyeing,etc.