Medically EGFR, or epidermal growth factor receptor, is a membrane surface sensor with tyrosine kinase activity that is commonly expressed in human epidermal cells and stromal cells and is highly expressed in a variety of human malignancies, such as non-small cell lung cancer and breast cancer. Therefore, clinically, the type of malignant tumor can be clarified by testing whether EGFR gene is mutated, and then targeted therapy can be applied. EGFR tyrosine kinase inhibitors, which can selectively act on intracellular target targets to block the function of EGFR and inhibit tumor progression, are clinically known as targeted drugs. Patients with EGFR gene test, if found to have exon 18, 19, 21 mutation, can consider using targeted drug therapy, commonly used drugs are Gefitinib, Occitinib, Erlotinib, etc. During the treatment period, the patient should pay attention to the review of lung CT to assess the effect of treatment, and if drug resistance occurs, it is necessary to change the drug or change other treatment options.