Objective To investigate the effect of Bufeihuoxue (BH) capsule, a Chinese Traditional Medicine, on pulmonary function in patients with chronic obstructive pulmonary disease (COPD), and to explore its possible mechanism. Methods A total of 170 COPD patients admitted in our hospital from March 2010 to March 2012 were subjected in this study. They were randomly divided into 2 groups, one group of patients were given regular COPD treatment (routine treatment group, n＝50), and the others were given BH capsule combined with conventional therapy (combined treatment group, n＝120). The pulmonary function, including forced expiratory volume in one second (FEV1) and forced vital capacity rate of one second (FEV1/FVC) was tested in 2 groups of patients. Acute outbreak of COPD was recorded. Serum levels of C-reactive protein (CRP), fibrinogen (Fib) and D-dimer (D-D) were determined by enzyme-linked immunosorbent assay (ELISA) before and after treatment. Results Compared with routine treatment group, combined treatment group had significantly improved lung function, especially shown as elevated FEV1/FVC, and decreased times of acute outbreak, and reduced serum contents of CRP, Fib and D-D (P＜0.05). Conclusion BH capsule can improve lung function in patients with COPD, and its mechanism may be related to the improvement of patients’ inflammatory reaction and pulmonary microvascular blood flow.