[Abstract]Chronic obstructive pulmonary disease (COPD) occurs mostly in middle-aged and elderly people, and patients often have poor quality of life and can also induce a variety of other lung diseases. At the same time, the lung cancer with the highest morbidity and mortality in the world, has claimed the lives of countless patients. Since the incidence of lung cancer is much higher in patients with COPD than in the general population, there are many links between the two diseases that need to be studied and explored. Although many studies have explored the association between the two, there are few studies on the molecular level of them. This review will focuse on the latest research progress of the pathogenesis of COPD complicated with lung cancer from four aspects: the role of chronic inflammation, programmed cell death, gene and molecular role and lung microbiome imbalance, so as to provide a new reference for the prevention, diagnosis and treatment of COPD complicated with lung cancer.