The invention provides oral liquid for effective treatment of oral ulcer. The oral liquid is prepared from traditional Chinese medicines of arnebia root, dandelion, natural indigo, red paeony root, yam rhizome, polyporus umbellate, reed rhizome, common lophatherum herb, root of Caragana sinica, cochinchnese asparagus root, plantain seed, perilla leaf, cattail pollen, motherwort herb, blackberrylily rhizome, redflower gentian herb, humifuse euphorbia herb, sowthistle tasselflower herb, capillary wormwood herb, tribulus terrestris, largeflowered lychnis herb, rhizoma arisaematis, roughhaired holly root, epimedium herb, root-bark of Chinese wolfberry and water chestnut. The oral liquid for effective treatment of oral ulcer has the efficacy of resolving mass, diminishing swelling, clearing heat, lowering fire, diminishing inflammation, relieving pain, clearing away the lung heat and regulating the stomach, and is capable of curing oral ulcer quickly, promoting cure of ulcerative surfaces, enhancing body resistance, and preventing recurrent ulcer so as to treat both manifestations and root causes of diseases. In addition, materials of the oral liquid are easily available, compatibility of medicines is reasonable, the preparation process is simple, no toxic and side effect is caused, the cure rate is high, and the oral liquid is worthy of wide popularization and application in clinical practice.