The invention discloses a preparation method of a
feed additive. The preparation method comprises the following steps: a step I, taking walnut green seedcases, crushing the taken walnut green seedcases to obtain walnut green seedcase granules, taking Chinese yam, making the taken Chinese yam into Chinese yam
starch paste, taking
glycine max, and making the taken
glycine max into fermented
glycine max; a step II, firstly taking radix astragali, haws, radix angelicae sinensis,
momordica cochinchinensis,
premna fulva craib,
radix isatidis, common
andrographis herbs,
pollen containing
bacillus thuringiensis, poria cocos, folium isatidis,
licorice roots, fructus aurantii, pseudo-
ginseng, lalang grass rhizomes, mulberry leaves, 10-20 parts of
radix bupleuri, radix scutellariae,
radix ophiopogonis and
lotus seeds, then performing uniform mixing, performing crushing to obtain mixed granules, then taking the walnut green seedcase granules, the Chinese yam
starch paste and the fermented glycine max, and uniformly mixing the walnut green seedcase granules with the Chinese yam
starch paste, the fermented glycine max and the mixed granules so as to obtain a primary
feed additive; a step III, soaking the primary
feed additive in tea soup for 24-48h; and a step IV,
drying the primary feed additive until the
water content is not more than 5% so as to obtain the feed additive.