Abstract: Optimum enzymes and their reaction conditions were determined after enzymatic properties of two kinds of thermostable α-amylases and two kinds of fungal-α-amylases had been studied. 30% maize starch was hydrolyzed by imported thermostable α-amylase and content of deoxidize sugar was 16.5% lastly, then 31.1% high purity maltose syrups which contained 1.7% glucose and 2.7% dextrin were obtained by Japanese fungal-α-amylase after reaction for 21 h under optimum conditions.