The impact of different first-line epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI)s to the clinical efficacy of osimertinib in EGFR-mutant non-small-cell lung cancer (NSCLC) patients with acquired T790M was still unclear. We enrolled 733 advanced EGFR-mutant NSCLC patients with gefitinib, erlotinib or afatinib as first-line EGFR-TKIs treatment for analysis. 373 patients received re-biopsies after progressive disease to first-line EGFR-TKIs treatment, and the total positive rate of T790M was 51.7%. 151 patients who harbored T790M received osimertinib as subsequent treatment. Among them, the median progression-free survival (PFS) of first-line EGFR-TKI (PFS1) was 14.0 months, and the median PFS of osimertinib (PFS2) was 10.1 months. The median PFS1 + PFS2 was 27.5 months, and the median overall survival from first-line EGFR-TKI was 61.3 months. Concerning different first-line EGFR-TKIs, the median PFS2 was 10.9 months in the gefitinib group, 10.0 months in the erlotinib group, and 6.7 months in the afatinib group (p = 0.534). The median PFS1 + PFS2 was 27.7 months, 26.8 months and 24.0 months in the gefitinib, erlotinib, and afatinib group, respectively (p = 0.575). In conclusion, both first-generation and second-generation EGFR-TKIs sequential osimertinib treatment provided good clinical efficacy in advanced EGFR-mutant NSCLC patients with acquired T790M mutation.