<b>Context:</b> Liuweibuqi (LWBQ) capsule has been reported to influence symptoms of patients with chronic obstructive pulmonary disease (COPD); however, specific function of LWBQ capsules in COPD with lung-qi deficiency syndrome remains elusive.<b>Objective:</b> This study investigates effect of LWBQ capsules on STAT4/STAT6 and MMP-9/TIMP-1 expression and pulmonary function in stable COPD with lung-qi deficiency syndrome.<b>Materials and methods:</b> Totally, 429 patients diagnosed with stable COPD and lung-qi deficiency syndrome were treated with starch capsules (each time for 9 capsules), or different doses: low (each dose for 8 capsules and 1 LWBQ capsules), medium (each time for 6 capsules and 3 LWBQ capsules), or high (each time for 9 LWBQ capsules) of LWBQ capsules for 30 days, 3 times a day.