Non-Small-Cell Lung Cancer（NSCLC）is one of the malignancies with high incidence and mortality. Epidermal growth factor receptor (EGFR) is implicated in NSCLC pathogenesis. Certain patient subgroups with NSCLC (ie, women, never-smokers, East Asians,adenocarcinoma) have higher rates of EGFR mutations, rendering them more responsive to EGFR tyrosine kinase inhibitors (TKIs; eg, gefitinib, erlotinib, Icotinib). Among patients with advanced EGFR-mutated NSCLC, treatment with EGFR-TKIs is associated with response rates of 56 to 74% and a median progression-free survival(mPFS) of 10 to 14 months;both outcomes are superior to those with platinum-based chemotherapy. Despite initial responses to EGFR-TKIs, the majority of patients will have disease progression within 1 to 2 years after treatment initiation (acquired resistance). In approximately 60% of patients, the mechanism of acquired resistance is the development of an additional EGFR mutation, EGFR T790M. Although AZD9291 (AstraZeneca), a third-generation EGFR-TKI is reported with a response rate of 61% in NSCLC patients with EGFR T790M and a mPFS of 9.6 months, resistance to third-generation inhibitors mediated by EGFR C797S mutation is inevitable. Therefore, optimizing the effect of each generation of EGFR-TKI is essential for long-term survival of NSCLC.The investigators' preliminary studies have shown that combining Yiqi-yangyin-jiedu decoction (YYJD) with gefitinib can prolong PFS and improve QOL, but high-level evidences are needed.