Abstract:α-Amylase is one of the most extensive enzyme for food and fermentation industry.Several thermostable α-Amylase enzymatic activity effect was studied from the optimal temperature，the optimal pH，the storage temperature and buffer solution pH.The results showed that B company's thermostable α-Amylase acid resistance was preferably with the relative activity of 98%to 100%between 4.00-7.50 pH and A company's thermostable amylase temperature resistance was the best with the relative activity 100%to 121%between 70℃-100℃and the thermostable α-Amylase of Company A buffering ability was the best in a buffer solution pH value between 4.50-7.00 with the activity from 91%to 100%and the E company's α-Amylase have the best temperature stability from 30℃to 60℃storage temperature with the relative activity of 98%to 100%. This research will provide the basis for the select of α-Amylase.