The invention relates to a concentrated oral solution for treating recurrent oral ulcer by type of fire excess from yin deficiency, which can be used for effectively solving the problems of poor curative effect, hard healing, long treatment cycle, high side effect, more impurities, low extract utilization, low content of effective components, poor administration effect and inconvenience in carrying. The oral solution is prepared from adenophora tetraphylla, coptis chinensis, salviae miltiorrhizae, dendrobium, unprocessed rehmannia root, radix scrophulariae, rhizoma anemarrhenae, yam, fructus forsythiae and radices trichosanthis by the following steps: washing the components, mixing, decocting twice, filtering, concentrating, and combining the filtrates; concentrating to obtain extract, standing, taking supernate, and adding a honey and cane glucose mixture or a glycyrrhizin solution or a stevioside solution; adding sodium benzoate, boiling to dissolve; adding water, uniformly stirring, refrigerating and centrifugally separating the supernate; and performing ultrafiltration on the supernate by an ultrafiltration membrane, encapsulating the ultrafiltrate, and sterilizing. The concentrated oral solution is small in side effects, increased in concentration and content of effective ingredients, small in dosage and convenient to take and carry, and is suitable for patients who cannot decoct decoction or are difficult to take medicines.