The invention relates to a feed additive, which comprises the following components by weight percent: 30 to 50 lactic acid bacteria, 30 to 50 Lactobacillu lantarum, 5 to 15 Saccharomyces cerevisiae and 5 to 15 sporeformer. By adopting the feed prepared by the feed additive, the quantity of the Probiotics inside the animal intestinal canal is increased, so the pathogenic bacterium in the excrementand secretion of the animals can be reduced, the inhibition substances such as hydrogen peroxide, bacteriocin and the like can be produced so as to inhibit the growth of putrefactive bacterium insidethe intestinal canal, to reduce the activity of the urease, to reduce the harmful substances such as ammonia, amine and the like and to favor the healthy growth of the animals; and at the same time, since the animals take the probiotics such as bacilus subtilis, Bacilus subtilis, Lactobacillus acidophius and the like, the micro-ecological environment inside the intestinal canal can be improved, the internal and external environments of the animal can be purified, the disease can be reduced, the balance of the micro-ecology can be adjusted, the absorption capacity of the intestinal canal can be strengthened, the nutrition digestion absorption can be promoted, the lymphocyte can be activated, the immune globulin and the antibody level can be improved, and the disease can be reduced.