The invention relates to a condensate bacillus feed additive and a preparation method, belonging to the technical field of microbial feed additives. The additive uses one or several of the fish meal, soybean meal, cottonseed meal, urea, ammonium sulfate, diammonium hydrogen phosphate, soybean peptone and yeast extract as the nitrogen source, and also takes one or several of the glucose, lactose, starch, cane sugar, maize flour and bran as the carbon source for fermentation; the number of viable bacteria reaches more than 1 multiplying 109 CFU/ml; after the additive is further concentrated and dried or directly adsorbed to the carrier, bacillus powder is obtained through spray-drying, and the number of viable bacteria reaches more than 1 multiplying 1010 CFU/g. The novel bacillus product produced with the submerged liquid fermentation method provided in the invention is free from toxic side effects, drug resistance and residue; the product can endure processing, intestinal habitat and storage.