Abstract: As a new type of non-toxic and pollution-free feed additive of biological products,animal microecological preparation had functions,in which the other additives could not replace it,such as adjusting the microecological balance in animal organism,preventing disease,enhancing the transform rate of feed,promote animal health and protecting ecological environment. And as the action mechanism was studied thoroughly,its effects were more obvious and its application was wider and wider. The reagent kinds,action mechanism,effect and application prospect of animal microecological preparations applied in pig production in recent years were summarized.