The invention provides a traditional Chinese medicine composition for treating oral ulcer, which is characterized by being prepared from the following traditional Chinese medicine raw materials: coptis roots, baikal skullcap roots, phellodendron bark, kuh-seng, prunella vulgaris, aloes, lotus leaves, radix zanthoxyli, radix berberidis, oriental waterplantain rhizome, snake slough, giant knotweed, bighead atractylodes rhizome, honeysuckle flowers, finger citron, dragon blood, talcum, ophiopogon roots, evodia rutaecarpa, herba cistanche, glossy privet fruits, eclipta, bezoar, mirabilitum praeparatum, ginkgo leaves, kudzu roots, pinellia tuber, cassia twigs, hyacinth bletilla, blackberrylily rhizome, achyranthes roots and humifuse euphorbia herbs. The traditional Chinese medicine composition takes natural traditional Chinese medicines as raw materials; aiming at oral ulcer, the traditional Chinese medicine composition takes the principles of clearing internal heat from blood, relieving toxicity and eliminating swelling, soothing the liver and regulating the flow of qi as well as promoting tissue regeneration by astringency, and dialectical compatibility of the medicines is carried out so as to achieve the aim of treating both symptoms and root causes; and the traditional Chinese medicine composition is exact in curative effect, free of toxic or side effect and capable of effectively treating oral ulcer and preventing relapse.