Feed additive and preparation method thereof

The invention relates to a feed additive and a preparation method thereof, belonging to the technical field of feeds. The feed additive is characterized by comprising the following substances in percentage by weight: 40 percent to 60 percent of dogwood, astragalus, medlar and licorice extract, 30 percent to 50 percent of honeysuckle flower, cortex eucommiae, okra and mimosa pudica extract, 5 percent to 10 percent of fish meal, 0.5 percent to 1 percent of selenium yeast, 0.1 percent to 0.5 percent of compound vitamins, 0.1 percent to 0.2 percent of compound amino acids and 2 percent to 5 percent of spirulina. The feed additive has the advantages of rich raw material sources, low price, no toxic or side effects, effects of preventing various diseases of laying hens and improving immunity and disease resistance of the laying hens, environment-friendliness, high safety, high laying rate, high laying quality, high survival rate of the laying hens, enrichment of selenium, iodine, zinc and other nutrient elements, and the like.