Objective: To investigate the influence of Danshen Injection on airway inflammation and CD4+CD25+ regulatory T cells(CD4+CD25+ Tr) of asthmatic rats, and elucidate the possible mechanism of Dansben Injection in treatment of asthma.Methods: 30 Wister rats were randomly divided into control group, asthma group and Danshen Injection treated group. Bronchoalveolar lavage fluids (BALF) were collected, and cytology studies were conducted. Lung tissues were obtained and pathologic analyses were done with hematoxylin and eosin stain (HE). Flow cytometry was used to detect the CD4+CD25+ Tr ratio in peripheral blood mononuclear cells (PBMCs). Results: Total cell, the percentage of lymphocytes, neutrophils and eosinophils (Eos) in BALF of Danshen Injection-treated group were lower than that in asthma group (P＜0.05, P＜0.01). Compared with asthma group, less infiltration of inflammatory cells in lung tissues was observed in Danshen Injection-treated group. CD4+CD25+ Tr of asthma group was lower than that of control and Danshen Injection treated group (P＜0.05). Conclusion: Danshen Injection can suppress airway inflammation of asthmatic rats, probably by increasing the number of CD4+CD25+ Tr.