The invention discloses a compound herb plant medicament for treating porcine diarrhea and a preparation method thereof .Raw materials of the compound herb plant medicament include roots of Littleleaf Breynia, licorice roots, poria cocos, Szechwan Lovage rhizomes, costus roots, cassia barks, asarum, an ephedra herb, aconiti rots, radix scrophulariae, cortex phellodendri, radix aconiti, distiller's yeast, root barks of the peony trees, radix angelica sinensis, ginkgo leaves, astragalus roots, half lotus support, sedum sarmentosum, radish seeds, indigowoad leaves, betel nuts, cherokee rose fruits, isatis roots, herba portulacae, rhizoma coptidis, dandelion, honeysuckle, white paeony roots and Chinese prickly ash .The compound herb plant medicament is prepared from pure Chinese herbal medicines, can effectively kill viruses causing porcine epizootic diarrhea and swine transmissible gastroenteritis, is especially applicable to the cases having not obvious antibiotic treatment effects, can fully embody the overall concept and advantages of traditional Chinese medicines, makes the efficacy and functions more comprehensive, treats both symptoms and root causes and has the advantages of being green and environmentally friendly in composition, simple and reasonable in process, low in manufacturing cost, good in prevention and treatment effect and small in side effect .