 This study is prospective to identify biomarkers to resistant to afatinib,gefitinib and erlotinib in non-small cell lung cancer patients. Mutations of whole exon of 295 gene are analysed by deep sequencing in Chinese patients with non-small cell lung cancer and their relationships with the patients clinical features including sex, age, smoking history and adenocarcinoma subtype, specify the predictive significance of the genes mutations for new targeted therapies in NSCLC patients, and better understand the molecular mechanism drug resistance to EGFR-TKIs. 