【Abstract】 The first epidermal growth factor receptor tyrosine kinase inhibitor (EGFRTKI) is widely used in EGFR mutation of advanced nonsmall cell lung cancer (NSCLC) treatment, the majority of patients received more than two years of survival, but acquired resistance has limited its use to clinical curative effect, more than 50% of exon 20 for drug resistant patients exon housekeeping gene EGFR T790M mutation. Afatinib is the second generation of irreversible anti human epidermal growth factor receptor (HER) in recent years, scholars have found that the preparation can inhibit the growth of T790M mutations in tumor cells, still have a certain effect on the use of a generation of EGFRTKI resistant NSCLC patients, but the mechanism is still not clear. This review will review the progress in the study of drugresistant advanced nonsmall cell lung cancer (NSCLC) caused by mutations in T790M gene and provide a new reference for the study and treatment of T790M mutant NSCLC.