Abstract： Objective： To observe the clinical effect of Liuwei Dihuang Pills combined with Kangfuxin Liquid for recurrent aphthous ulcer. Methods：A total of 170 cases of recurrent aphthous ulcer patients were divided into the control group and the treatment group according to the random number table method，with 85 cases in each group. The control group was treated with Kangfuxin Liquid，and the treatment group was additionally treated with Liuwei Dihuang Pills based on the treatment of the control group. Both groups were treated for 15 days. The changes symptom and signs scores， pain scores， and levels of CD3 + ， CD4 + ， CD8 + ， CD4 +/CD8 + of T lymphocyte subsets before and after treatment， the clinical effects， and the incidence of adverse reactions were compared between the two groups. Results：The total effective rate was 96.47% in the treatment group and 87.06% in the control group，the difference being significant (P＜ 0.05). Before treatment，there was no significant difference being found in the comparison of symptoms and signs scores and Visual Analogue Scale(VAS) scores between the two groups (P＞0.05)； after treatment，symptoms and signs scores and VAS scores in the two groups were decreased when compared with those before treatment (P＜0.05)，and the symptoms and signs score and VAS score in the treatment group were lower than those in the control group (P＜0.05). Before treatment， there was no significant difference being found in the comparison of the levels of CD3 + ， CD4 + ， CD8 + ， and CD4 +/CD8 + of T lymphocyte subsets between the two groups (P＞0.05). After treatment， CD8 + levels in the two groups were decreased when compared with those before treatment (P＜0.05)，and the levels of CD3 +，CD4 +， and CD4+/CD8+ were increased when compared with those before treatment (P＜0.05)；CD8+ level in the treatment group was lower than that in the control group (P＜0.05)，and the levels of CD3 +，CD4 +，and CD4 +/CD8 + were higher than those in the control group (P＜0.05). The incidence of adverse reactions was 3.53% in the treatment group and 8.24% in the control group， there being no significant difference between the two groups (P＞0.05). Conclusion： Liuwei Dihuang Pills combined with Kangfuxin Liquid for Recurrent aphthous ulcer can significantly enhance the clinical effect，relieve pain，and improve immune function of patients and TCM syndrome.