Alpha amylase (E.C. 3.2.1.1) is one of the most important starch-degrading enzymes and widely applied in pharmaceutical, food, feed, detergent, textile and bio refinery industries. The present work was focused on optimization of ɑ-amylase production using the bacteria strain Bacillus amyloliquefaciens in submerged cultivation system. The results showed that, the optimal soluble starch concentration for maximal enzyme production of 1950 µkat.L-1 was 20 g.L-1. Compared to shake flask, bioreactor batch cultivation yielded higher volumetric enzyme production of 4125 µkat.L-1 (about 1.84-folds higher than the value obtained in shake flask). In addition, fed-batch cultivation with two feeding strategies (constant feeding and increased feeding) was also designed to improve the production process. The maximal volumetric enzyme production of 8160 µkat.L-1 was obtained in increased feeding strategy after 36 hours of cultivation. This value was almost 98 and 18% higher than the enzyme produced in batch and constant feeding fed-batch cultivations, respectively.