As the composition of the lung microbiome becomes clearer，studies have shown that changes in the diversity or abundance of microbes in the lung are closely linked to chronic obstructive pulmonary disease （COPD）. In COPD，lung microbiome can affect the body′s immune activities by activating airway TLR，recruiting and activating immune cells，and promoting airway mucus secretion，thus exacerbating airway inflammation. In addition，lung microbiome is also involved in oxidative stress of COPD. At the same time，the imbalance of lung microbiome may lead to acute exacerbation in stable COPD patients. The mechanism of lung microbiome in COPD is not well understood，this article reviews the relationship between lung microbiota and COPD.