The invention discloses a traditional Chinese medicine preparation for treating rectal cancer and a preparation method thereof and belongs to the field of traditional Chinese medicines. The traditional Chinese medicine preparation comprises the following raw materials: semen boitae, artocarpus heterophyllus, picrorhiza scrophulariiflora pennell, Yunnan bulbophyllum herb, averrhoa carambola, polygonum runcinatum, bauhinia purpurea, subprostrate sophora, viburnum cylindricum leaves, citrus aurantium, rubus idaeus, folium nelumbinis, carica papaya, radix puerariae, bidens pilosa and fructus chebulae. The traditional Chinese medicine preparation and the preparation method thereof have the benefits that the medicinal materials selected by the traditional Chinese medicine preparation are reasonable in compatibility, and the traditional Chinese medicine preparation conforms to the theory of traditional Chinese medicine and pharmacy and modern medicine and pharmacology, has the efficacies of regulating the flow of Qi and removing blood stasis, clearing away heat and detoxifying, and dispelling wind and eliminating dampness, has a special treatment effect on the rectal cancer caused by various inflammations, has the advantages of high simplicity in the manufacture of the medicinal materials, good convenience for taking, high safety and reliability, no any toxic and side effects, low cost and obvious treatment effect, can achieve the purpose of treating both symptoms and root causes in the treatment of the rectal cancer and is worthy of wide clinical popularization and application.