The invention provides a method for preparing a feed additive by using bacillus licheniformis. The method comprises the following steps of: preparing and activating a strain, preparing a strain with an inclined surface, preparing a triangular flask liquid strain, fermenting a canned solid and the like so as to obtain the feed additive. By adopting a unique culture medium and a solid fermentation technique, the strain propagation speed is accelerated, the fermentation period is shortened, the production cost is lowered, and the spore forming rate of a product is increased; a cheap medium such as bran is used as a main culture substrate, so that the production cost is effectively lowered; the production process has the unique advantages of water conservation, energy conservation, small quantity of byproducts and environment friendliness; and the production cost is low, the product is resistant to high temperature, acid, alkali and extrusion, is small in damage in the preparation process of the feed, small in adding quantity and remarkable in feeding effect, so that the method belongs to a sanitary production technique and has large-scale popularization and application values.