This is an open-label, multicenter, single-arm, phase II interventional clinical trial evaluating efficacy and safety of Icotinib as neoadjuvant treatment in patients with IIIA- IIIB NSCLC with activating EGFR mutation in exon 19 or 21. Sixty-seven resectable stage IIIA- IIIB NSCLC patients with EGFR activating (19/21) mutations will be eligible to be enrolled. EGFR mutation will be prospectively tested in all the participants' biopsy samples and confirmed in surgical resected samples.