Abstract： Objective： To observe the clinical effect of Wenfei Jianpi Huatan prescription assisting routine western medicine for bronchial asthma at chronic duration. Methods：A total of 102 cases of patients with bronchial asthma at chronic duration were selected and divided into the observation group and the control group according to the random number table method，51 cases in each group. The control group was treated with routine western medicine，and the observation group was additionally treated with Wenfei Jianpi Huatan prescription based on the treatment of the control group. The clinical effect after treatment in the two groups was compared. The lung function and the levels of costimulatory molecule B7- H3，heat shock protein 70(HSP70)，eosinophilic cationic protein(ECP) and interleukin-35(IL-35) were detected. The Chinese medicine syndrome scores and asthma control test(ACT) scores were counted. Results：After treatment，the scores of phlegm drool， acute panting and fullness in the chest，inability to lie flat，bluish and dark complexion in the two groups were all lower than those before treatment， and the above symptom scores in the observation group were lower than those in the control group，differences being significant(P＜0.05). After treatment，the levels of forced expiratory volume in one second(FEV1)， peak expiratory flow(PEF) and peak expiratory flow rate(PEFR) in the two groups were increased when compared with those before treatment， and the above levels in the observation group were higher than those in the control group， differences being significant(P＜0.05). After treatment，the levels of IL-35 in the two groups were increased when compared with those before treatment， and the levels of B7- H3， HSP70 and ECP were decreased， and the indexes in the observation group were better than those in the control group，differences being significant(P＜0.05). After treatment，the ACT scores in the two groups were increased when compared with those before treatment，and the recurrent numbers within half a year were decreased when compared with those before treatment； ACT score in the observation group was higher than that in the control group， and the recurrent number within half a year was fewer than that in the control group， differences being significant(P＜0.05). Conclusion：Wenfei Jianpi Huatan prescription assisting routine western medicine for bronchial asthma at chronic duration can regulate the expression levels of B7-H3，HSP70，ECP and IL-35，improve the lung function，relieve symptoms and reduce recurrence.