Lung cancer is the leading cause of cancer-related deaths worldwide，and in the past few years，many studies have found that gut flora has an important role in the development of lung cancer. The intestinal microbiota is considered as a human microbial organ，which not only affects the human body’s functions such as digestion and anti-infection，but also influences the human body’s response to tumor therapy by participating in immunomodulation and metabolism. In addition，the interaction between microorganisms and host cells is crucial for regulating local and systemic physiological functions，which can influence the local microenvironment and immune system function of the host，thus affecting tumor development and anti-tumor therapeutic effects. In this paper，we will review the mechanisms by which intestinal flora influence lung cancer development and their clinical significance in lung cancer treatment.