The invention discloses a traditional Chinese medicine composition for treating oral ulcer. The traditional Chinese medicine composition is prepared from the following active pharmaceutical ingredients: gypsum, calamine, natural indigo, borneol, dried alum, dark plum fruit, mint, oyster, pearl, calculus bovis, radix scutellariae, coptisine hydrochloride, coix seed, amur corktree bark, radix sophorae flavescentis, licorice roots northwest origin, Chinese gentian root, Chinese gall, dandelions, sediment of human urine, realgar, carbonized spider, ivory chips, abroma angusta, wusuli dragonflyorchis rhizome, anhydrous sodium sulphate and alumen. The composition has the functions of clearing away heat and toxic materials, relieving swelling and pain, removing necrotic tissue and promoting granulation and astringing to stop bleeding, is mainly used for treating oral ulcer caused by endogenous pathogenic heat, has simple preparation processes and small toxic and side effects, is convenient to administrate, is easy to prepare, is low in cost, can directly treat focuses, ensures short cure time and avoids relapse after cure.