Abstract： Objective To investigate the curative effect of Zhigancao Decoction(炙甘草汤)on patients with refractory recur-rent oral ulcer.Methods A hundred and ninety-six patients with recurrent oral ulcer admitted to the hospital were divided into the control group(98 cases)and the treatment group(98 cases)from January 2019 to December 2021 by the distribution principle of random number table.The control group was treated with compound vitamin B tablets,vitamin C tablets and Cydiodine Tablets.The treatment group was treated with Zhigancao Decoction on the basis of the control group.Both groups were treated for 2 weeks and followed up for 1 year.The curative effect after 2 weeks of treatment,the clinical symptom improvement and recurrence,the scores of traditional Chinese medicine symptoms,pain degree,sleep quality,quality of life,the levels of inflammation,immune in-dexes and the safety during treatment were compared between the two groups.Results Compared with the total effective rate(84.69％,83/98)of the control group after 2 weeks of treatment,the total effective rate of the treatment group was higher(93.88％,92/98)(P＜0.05).Compared with those of the control group,the times of ulcer pain improvement and ulcer healing in the treatment group were shorter(P＜0.05).Compared with the total recurrence rate of the control group during the followed-up period(13.27％,13/98),the total recurrence rate of the treatment group(5.10％,5/98)was lower(P＜0.05).After 2 weeks of treatment,the scores of dull ulcer pain,repeated attacks,dry mouth and bitter mouth,abdominal distension,visual analogue scale(VAS)score,pittsburgh sleep quality scale(PSQI)score,the levels of whole blood CD8+,the levels of serum tumor necrosis factor-α(TNF-α)and interleukin-2(IL-2)in the treatment group were lower than those before,the indexes of the treatment group were lower(P＜0.05).The score of quality of life scale(QOL-100)and the levels of whole blood CD4+and CD4+/CD8+in the two groups were higher than those before,and the levels of the treatment group were higher(P＜0.05).There was no nausea,vomiting,rash or dizziness in the treatment group and the control group during the treatment.Conclusion Zhigancao Decoction could effectively regulate the levels of inflammation and immune indicators in patients with refractory recurrent oral ulcer,reduce the body inflammation,improve the immune function,the degree of pain,sleep and quality of life,which could further promote the improvement of traditional Chinese medicine symptoms and clinical symptoms and prevent the recurrence,with significant effect and higher safety.