The invention relates to a pig feed additive capable of replacing antibiotics, and a preparation method and an application thereof. Components and weight part ratio thereof in a formula are as follows: 1-5 parts of medicated leaven, 1-5 parts of angelica sinensis, 1-5 parts of radix astragali, 1-5 parts of hawthorn, 1-5 parts of radix codonopsis, 10-20 parts of citric acid, 10-20 parts of lactic acid, 20-30 parts of coated phosphoric acid, 5-10 parts of a micro-ecological preparation, 5-10 parts of yeast cell wall polysaccharide, 1-5 parts of a composite plant essential oil and 5-10 parts of a carrier. The pig feed additive carries out combination collocation of traditional Chinese herbs and functional polysaccharide, the micro-ecological preparation, acidifying agents, plant essential oil and the like, so that synergic effect of the traditional Chinese herbs and other components are maximized; the pig feed additive can replace the antibiotics completely; problems of drug resistance, drug residues, overcommitment and the like of the antibiotics which trouble animal husbandry for a long time is reduced; and at the same time, the pig feed additive plays effects of improving culture environment, reducing feed safety hidden dangers, increasing culture benefits and the like.