The invention relates to a veterinary medicine composition and a preparation method thereof. An intestinal virus syndrome vaccine oral liquid synergistic agent is mainly prepared by the following raw materials by weight portion: 10 to 20 portions of atractylis ovata, 15 to 25 portions of dangshen, 10 to 20 portions of sweet wormwood herb, 10 to 25 portions of medicine terminalia fruit, 20 to 25 portions of pomegranate bark, 15 to 20 portions of Flos Poprli, 10 to 20 portions of alisma orientale, 2 to 5 portions of snake gall, 10 to 20 portions of ox-gall, 40 to 60 portions of Chinese aloe, 25to 40 portions of crystal sugar, 18 to 25 portions of neomycin, 10 to 16 portions of oxytetracycline hydrochloride and 8 to 10 portions of sulfamethoxazole sodium. The oral liquid synergistic agent can eliminate toxin in blood and toxin invaded from the outside of organisms, has the characteristic of clearing away heat and toxic materials, can kill fungus, mold and bacteria, inhibit and eliminategrowth and propagation of pathogens, and treat the intestinal virus syndrome. Moreover, the oral liquid synergistic agent has the advantages of convenience in drinking and administration, high absorptivity, wide distribution, no medicine residue, no toxic side effect, and wide safe range.