Microorganisms are increasingly studied in the process of tumorigenesis and development in various organs of human body, the concept of disease entering by the mouth reveals that the oral cavity is the first organ where microorganisms enter the human body. Therefore, the role of oral microorganisms in relation to tumors cannot be ignored. It has been found that the composition of oral microbial communities in healthy populations is almost the same as that of lung microbial communities, and oral microbes may influence the composition and diversity of lung microbes through the oral-lung axial pathway, thus exerting an important influence on the development of lung tumors and other diseases. However, their exact roles in diseases such as lung tumors are unknown, and understanding the relationship between oral microbes and lung tumors is important for the prevention and treatment of diseases such as lung cancer. This review focuses on the possible oncogenic mechanisms of oral flora closely related to lung cancer as well as potential therapeutic approaches, etc. On the basis of this review, the prospect of oral flora in the basic research of lung cancer is envisioned with a view to providing useful references for future research.