Abstract： Aim To evaluate the effect of sublingual immunotherapy(SLIT)on bronchial asthma(BA)and its influence on the levels of Interleukin(IL)-17 and IL-27 and the balance of T helper cell 17/Regulatory T cells(Th17/Treg).Methods The clinical data of 124 BA patients were retrospectively collected.The patients were randomly divided into the observation group(n=62)and the control group(n=62)randomly.Both groups received conventional treatment after admission,that the control group re-ceived budesonide and formoterol powder inhalation,and the observation group received dust mite drops under the tongue based on the control group.The disease control status,clinical symptom scores,and the levels of IL-17 and IL-27 and the proportion of Th 17 and Treg cells in the peripheral blood were compared between the two groups.Results The total control rate of the observation group was higher than that of the control group(P＜0.05).After treatment,the clinical symptom scores,the level of Th17/CD4+and Th17/Treg in the two groups and IL-17 in observation group were lower than before treatment,and the observation group were lower than the control group(P＜0.05).After treatment,the level of IL-27,Treg/CD4+were higher than those before treatment,and those in the observation group were higher compared with the control group(P＜0.05).Conclusion SLIT has a good effect in the treatment of patients with BA,which can reduce the level of IL-17 in peripheral blood,increase the level of IL-27 in peripheral blood,and correct the immune balance of Th17/Treg in patients with BA.