Objective To observe the clinical curative effect and possible mechanism of modified Dingchuan San（ 定喘散） combined with Seretide in the treatment of bronchial asthma. Methods Totally 100 patients with bronchial asthma were randomly divided into a treatment group and a control group

with 50 cases in each group. Both groups were given inhaled Seretide 50 /250 μg

once every 12 h. At the same time the treatment group was added with modified Dingchuan San

1 dose per day. Course of treatment of both groups are three months. Changes in asthma control test（ ACT score）

lung function [including the aberration rate of forced expiratory volume in the first second（ FEV1 aberration rate） and the percentage account for predicated value of forced expiratory volume in the first second（ FEV1%） ]

serum levels of interleukin4（ IL-4）

tumor necrosis factor α（ TNF-α）

and γ interferon（ IFN-γ） in both groups in the first and third mouth before and after treatment were compared to determine clinical effects.Results Total effective rate of clinical effects was 96. 00% in the treatment group

and 84. 00% in the control group. The treatment group was better than that in control group（ P < 0. 05）. ACT scores in both groups in the first and third mouth after treatment were higher than that of the corresponding group before treatment

and FEV1 aberration rate

level of TNF-α and IL-4 decreased

and FEV1% increased（ P < 0. 05 or P < 0. 01）. Every index in both groups in the third month after treatment improved more significantly than that in the first month after treatment（ P <0. 05）. Compared with the control group in the first and third months after treatment

ACT score at the same time increased

but FEV1 aberration rate

TNF-α and IL-4 decreased

and FEV1% increased in the treatment group（ P <0. 05）. The INF-γ levels in the treatment group in the first and third month after treatment were higher than that before treatment（ P < 0. 05）. Conclusion Modified Dingchuan San combined with inhalation of Seretide may continuously improve symptoms and pulmonary function of patients with asthma

and could anti-inflammatory medium and regulate immune. The curative effect of modified Dingchuan San combined with Seretide is superior to only use Seretide.