The invention discloses a unique Chinese medicinal herb preparation special for treating canker sore (aphthous stomatitis). The vital movement of a person is the synergic reaction of viscera functions, and viscera have different functions and depend on and restrict mutually; and the viscera are applied in different ways and cooperate with one another. According to syndrome differentiation treatment of viscera diseases, symptoms on lips, tongue and oral cavity are caused by spleen qi stagnation of a patient suffering from aphthous stomatitis, wind-heat, anxious heat, deficiency-cold in middle-jiao, deficiency-fire in lower-jiao and channel and collateral progression. In the preparation, coptis root, figwort, dwarf lilyturf root, common anemarrhena, indigowoad leaf, isatis root and Chinese wolfberry root-bark are used for clearing away heat, purging pathogenic fire, reducing fever, detoxifying, nourishing yin, cooling blood, removing ecchymoses, eliminating stagnation, relieving sore throat and treating deficiency-heat; baikal skullcap root, amur corktree bark, natural indigo, Chinese angelica, dangshen, large-head atractylodes rhizome, indian buead and tree peony bark are used for clearing away heat, cooling blood, eliminating dampness, normalizing the function of the stomach and spleen, clearing dampness, promoting diuresis, purging pathogenic fire, detoxifying, invigorating the spleen, replenishing the stomach, enriching the blood, invigorating blood circulation and eliminating stasis; and unprocessed fructus gardenia, gypsum, unprocessed rehmannia, processed rehmannia, glossy privet fruit, spina date seed, shelled cedar seed, skunk bugbane and dragon bone are used for clearing away heat, purging pathogenic fire, relieving restlessness, quenching thirst, eliminating wetness, nourishing yin, promoting the secretion of saliva or body fluid, cooling blood, enriching the blood, nourish yin and kidney, converging, inducing astringency, subduing the liver yang, releasing mental stress and nourishing the heart to calm the mind till the aphthous stomatitis is cured. The preparation does not contain any chemical ingredient which is harmful to human bodies, has a small side effect, a remarkable curative effect and low production cost, and is easy to take.