The invention relates to a veterinary traditional Chinese medicine for treating fish diseases. The medicine is characterized by comprising the following components in parts by weight: 5-10 parts of folium isatidis, 4-8 parts of coptis chinensis, 6-12 parts of folium cortex eucommiae, 2-6 parts of Chinese Gall, 3-7 parts of acorus calamus, 8-15 parts of gingko leaf, 2-6 parts of pomegranate bark, 4-10 parts of scutellaria baicalensis, 8-15 parts of felwort, 3-8 parts of radix sophorae flavescentis, 6-12 parts of radix bupleuri, 5-10 parts of rheum officinale and 4-9 parts of common andrographis herb. The compound traditional Chinese medicine is synergetic and complementary in medicinal materials, has the effects of resisting bacteria, virus, bacterial endotoxin, fungus and parasite, improving immunity and promoting fish body growth and development, can simultaneously act on multiple targets of multiple diseases of fish, can be used for effectively preventing and treating hemorrhagic disease, septicemia, sepsis and other diseases caused by pathogenic bacterium / or bacterial products (such as bacterial endotoxin), parasite, virus and the like, and has remarkable preventing and treating effects on fish composite infectious diseases caused by multiple infectious agents.