Objective：To observe the clinical effect of Xiaoxian tang for oral lichen planus of yin deficiency with internal heat type.Methods：A total of 105 cases of patients with oral lichen planus of yin deficiency with internal heat type were selected as the study subjects and divided into the observation group and the control group according to the random number table method，55 and 50 cases in each group respectively.The control group was treated with routine western medicine，and the observation group was additionally treated with Xiaoxian tang based on the treatment of the control group.After treatment，the clinical effect in the two groups was compared.Results：The total clinical effective rate was 89.09% in the observation group，significantly higher than that of 70.00% in the control group(P ＜ 0.05).Before treatment，there was no significant difference being found in the comparison of the scores of Visual Analogue Scale(VAS)in the two groups(P＞0.05).After treatment for one，two and four weeks respectively，the scores of VAS in the two groups were decreased when compared with those before treatment，and the scores in the observation group were significantly lower than those in the control group in the same period，differences being significant(P ＜ 0.05).Before treatment，compared with the levels of indexes of immune function including CD4+，CD8+and CD4+/CD8+in the two groups，there was no significance in the difference(P＞ 0.05).After treatment，the levels of CD4+and CD4+/CD8+in the two groups were increased when compared with those before treatment，and the levels of CD8+were decreased when compared with those before treatment(P ＜ 0.05)；the levels of CD4+and CD4+/CD8+in the observation group were higher than those in the control group，and the level of CD8+was lower than that in the control group(P＜0.05).Conclusion：The therapy of Xiaoxian tang combined with routine western medicine has significant clinical effect in treating oral lichen planus of yin deficiency with internal heat type，and can effectively relieve pain and improve immune function，which is worthy of clinical promotion and application.