With Bacillus licheniformis in deep liquid fermentation and the process of exaction and refinement, it can randomly hydrolyze starch, hepatin and a-1.4 glucosidic bond in catabolite molecules to make the viscosity of colloidal starch solution decline, and to get the soluble dextrin and oligose. If the liquation time is prolonged, it can also get slight dextrose and maltose reducing thickness and helping liquation. So it is also called liquid amylase. It has good heat resistance and soon liquefies completely under high temperature with good flocculent dregs,evident delamination and quick filtration .The dosage of the amylase is very low and the process is simple, so the product has distinct excellence in the aspect of predigesting techniques, improving quality, reducing cost, saving energy and so on.