The invention discloses a sow feed additive as well as a preparation method and application thereof, and relates to the field of pig feed. The sow feed additive provided by the invention is prepared from the following components in parts by weight: 10-20 parts of selenium yeast, 10-20 parts of vitamin E, 3-10 parts of catechin, 10-20 parts of glutamine, 10-20 parts of safflower seed oil powder, 10-20 parts of dandelion hay powder and 15-25 parts of bean pulp. The formula of the sow feed additive is obtained by means of scientific and reasonable collocation; after being used for feeding sows, the sow feed additive can obviously increase the survival number and body weights of corresponding piglets, reduces the diarrhea rate of the piglets in lactation, enhances the immunity of the piglets, improves the health level of the piglets, and improves the growth performance of the piglets.