The invention discloses a goose feed additive and a preparation method thereof, wherein the goose feed additive comprises the following materials in parts by weight: 1-3 part of zinc sulfate, 0.3-0.5 part of lysine, 0.4-0.6 part of methionine, 1-3 parts of grape seed oil, 0.3-0.5 part of calcium hydrophosphate, 0.2-0.4 part of edible salt, 0.2-0.4 part of wintergreen oil, 1-3 parts of garlic, 0.5-1 part of honeysuckle, 0.5-0.8 part of scallion, 2-4 parts of Houttuynia cordata, 1-3 parts of poria cocos, 0.8-1.2 parts of herba pogostemonis, 0.3-0.5 part of radix aucklandiae, 0.1-0.3 part of fructus amomi, 0.2-0.4 part of coke yeast, 0.3-0.5 part of endothelium corneum gigeriae galli, 0.3-0.5 part of fern leaves and 0.2-0.4 part of radix polygonati officinalis. According to the invention, the expense for the formula is low, the materials are easily available, the preparation method is simple, and since garlic, honeysuckle, scallion and Houttuynia cordata are added in the feed, the goose feed additive has sterilizing effect and effectively adjusts the phenomenon of unhealthy intestines and stomach of goose; and poria cocos, herba pogostemonis, radix aucklandiae, fructus amomi, coke yeast, endothelium corneum gigeriae galli, fern leaves and radix polygonati officinalis prevent food preference of goose, enable the fatting effect to be obvious, and effectively overcome the defect of insufficiency of various nutrients.