The invention provides a Chinese herbal medicine feed additive for preventing and treating diarrhoea of poultry. The feed additive consists of the following raw materials of 40-70 parts of berberine, 10-20 parts of fructus gardeniae, 0.1-0.7 part of bitter bamboo leaves, 15-25 parts of dandelions, 4-5 parts of purslane herbs, 4-5 parts of discolorous clinquefoil roots, 2-3 parts of herba pteris multifida, 0.2-0.6 part of ligustici rhizoma et radix, 2-3 parts of dried flowers of gossampinus malabarica, 2-3 parts of radix sophorae flavescentis, and 1-2 parts of endothelium corneum gigeriae galli. The raw materials used for the Chinese herbal medicine feed additive are cheap in price, easy to purchase, and convenient to use, the Chinese herbal medicine feed additive can effectively realize the purpose of preventing and treating diarrhoea of poultry after being added to a daily feed of the poultry, and the Chinese herbal medicine feed additive is safe and free from side effects. The formula and the composition are scientific and reasonable, the technology is simple, the use is convenient, the cost is low, the Chinese herbal medicine feed additive not only can effectively improve the immunity of livestock and poultry, but also can well control enteritis diarrhoea caused by bacteria, viruses and the like.