A 61-year-old Chinese woman was diagnosed as primary pulmonary adenocarcinoma of left superior lobe with epidermal growth factor receptor (EGFR) 19 del mutation positive.Treatment with icotinib was given, but her disease progressed after 6 months remission. CT-guide needle biopsy for the new lesion in inferior lobe of left lung demonstrated intrapulmonary metastasis, and EGFR gene panel by Amplification Refractory Mutation System Polymerase Chain Reaction (ARMS-PCR) confirmed EGFRT790M mutation.Treatment with osimertinib was initiated. After 2 months remission, the disease progressed. Re-biopsy was performed for the tumor in the inferior lobe of left lung, and ARMS-PCR demonstrated no other gene mutation except EGFR 19 del. Icotinib was re-challenged, but disease progressed continuously. Bevacizumab was added, and partial response was achieved after 2-cycle of combination therapy.The non-small cell lung cancer (NSCLC) in this case maintained EGFR activating mutation and lost EGFRT790M mutation was a genetic change after osimertinib treatment.This case suggests the re-challenge of the first-generation EGFR-TKIs combined with bevacizumab may overcome the tumor resistance and prolong survival of NSCLC patient.