Abstract: Lactic acid bacteria（LAB） belong to the gram positive and facultative anaerobic bacteria, which can produce lactic acid, digestive enzymes and other active factors. These factors are able to maintain the balance of intestinal flora, improve the immunological function of host, and promote the digestive efficiency of nutrients. Therefore, LAB has become a common microbial feed additive and is widely used in animal production. This article summarizes the biological characteristics of LAB and introduces its application in animal nutrition, in hoping to provide theoretical basis for the experimental research and production practice of animal nutrition.