The T790M mutation is a drug-resistant mutation in non-small cell lung cancer patients after treatment with tyrosine kinase inhibitors targeting sensitive mutations in the EGFR gene. The EGFR gene, or epidermal growth factor receptor, is a membrane surface sensor with tyrosine kinase activity that is ubiquitously expressed in human epidermal and stromal cells, and is highly expressed in a variety of human malignant tumors, such as non-small cell lung cancer. If T790M mutation occurs, it is necessary to discontinue the tyrosine kinase inhibitor treatment as prescribed by the doctor, and replace the tyrosine kinase inhibitor that can be effective against T790M mutation, such as third-generation drugs, to avoid delaying the treatment and worsening the disease, and the use of drugs in accordance with the doctor’s instructions. If T790M mutation occurs, patients are advised to seek medical advice from a medical professional in a timely manner.