According to data released by the World Health Organization’s International Agency for Research on Cancer, the incidence of cancer worldwide will increase by 50 percent by 2020, and the number of new cancer patients will reach 15 million each year. The report also listed the top cancers with the highest incidence rate in the world, the first one being lung cancer with 1.2 million new patients per year, followed by breast cancer with about 1 million new patients per year, followed by bowel cancer with 940,000, stomach cancer with 870,000, liver cancer with 560,000, cervical cancer with 470,000 and esophageal cancer with 410,000. In the past 30 years, the mortality rate of lung cancer in China has increased by 465%, ranking first in the world, and has replaced liver cancer as the first cause of death from malignant tumors in China. Lung cancer is a malignant tumor originating from bronchial mucosa or glands. According to histopathology, lung cancer is divided into two categories: non-small cell lung cancer and small cell lung cancer. Among them, non-small cell lung cancer accounts for 80% to 85%. Non-small cell lung cancer and small cell lung cancer are completely different in terms of tumor biological behavior and responsiveness to treatment, and therefore treatment varies. Non-small cell lung cancer is highly malignant, and more than half of these patients are advanced at the time of initial diagnosis and lose the opportunity for surgery. The median natural survival of advanced non-small cell lung cancer without treatment is about 4-5 months, and the 1-year survival rate is less than 10%. In addition most patients will eventually develop recurrence and metastasis after treatment. For the past 30 years, chemotherapy has played an important role in the treatment of NSCLC, but its effectiveness and survival benefit have been very limited. In advanced NSCLC, a two-drug platinum-containing regimen has an objective efficiency of 30C40% and a median survival time of 8-10 months. In recent years, a new term, molecularly targeted drugs, has emerged in the treatment regimen of non-small cell lung cancer, and its miraculous efficacy has brought a new light to the treatment of lung cancer. Molecular targeted therapy refers to targeting the key macromolecules in the process of tumor occurrence and development, controlling the gene expression and changing the biological behavior of tumor cells by specifically blocking their signaling, or inhibiting the growth and reproduction of tumor cells by preventing tumor angiogenesis, thus playing an anti-tumor role. Currently, molecular targeted therapies are mainly divided into those targeting epidermal growth factor receptor (EGFR) and those targeting tumor angiogenesis (VGFR), mainly including epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) – gefitinib, erlotinib, crizotinib, which inhibits EML4/ALK fusion protein, anti-EGFR monoclonal antibody – cetuximab. antibody – cetuximab, and anti-VEGF/VEGFR monoclonal antibody – bevacizumab, anti-vascular endothelial cell agents – human vascular endothelial inhibitor (Endo), etc. Molecular targeted therapy has great advantages compared with traditional chemotherapy. 1. Individualized treatment becomes possible. For example, the efficiency of EGFR-TKI treatment for non-small cell lung cancer with EGFR mutation is over 90%, so the treatment efficacy can be predicted by tissue EGFR detection. 2. Target specificity and mild toxic side effects. Unlike cytotoxic chemotherapy, targeted drugs tend to target abnormal mutated sites, so the target is specific and has less impact on normal tissue cells, thus the gastrointestinal reactions and hematological toxicity are mild and easily tolerated by patients. 3.The treatment method is simple and easy to use. At present, many targeted drugs are administered orally, with good patient compliance and tolerance, and can be administered in outpatient clinics and at home, which is easily accepted by patients. 4.Improve the quality of life. For advanced tumor patients, cytotoxic drugs can prolong the survival of some patients, but the side effects are large and make patients fear of treatment. While targeted drugs can usually improve patients’ symptoms rapidly and the side effects of treatment are small. 5, the combination of molecular targeted drugs and chemotherapy can improve the efficacy. For example, the combination of anti-angiogenic drugs and chemotherapy can significantly improve the efficiency without any significant increase in toxic side effects. Although molecular targeted drugs are increasingly used in the treatment of non-small cell lung cancer, the gradual emergence of drug resistance has become a major clinical problem. Current studies have shown that multiple molecular mechanisms are involved in the development of drug resistance, and the exact mechanism of drug resistance needs to be further explored and studied, which is of great significance for us to formulate effective preventive treatment regimens, discover effective markers to predict drug resistance, and better select drugs to bring benefits to cancer patients.