This is a Phase 2, prospective, randomized, open-Label, single-center international study that assesses the efficacy and safety of neoadjuvant therapy with different cycles of sintilimab combined with chemotherapy for resectable NSCLC. In this trial, eligible subjects will be randomly assigned to arm A and arm B (1:1). Subjects in arm A will receive 2 cycles of neoadjuvant chemotherapy with sintilimab + chemotherapy and arm B will receive 3 cycles of neoadjuvant chemotherapy with sintilimab + chemotherapy, followed by surgery within the 4th week after the last dose of sintilimab. After operation, subjects in arm A will receive 2 cycles of adjuvant chemotherapy and arm B will receive 1 cycle of adjuvant chemotherapy, followed by the maintenance treatment of sintilimab for up to 1 year according to the requirements of patients. The primary purpose is MPR rate of neoadjuvant chemotherapy of resectable NSCLC with different cycles of sintilimab combined with platinum-based chemotherapy, which is defined as the percentage of participants having 10% viable tumor cells in the pathological examination of resected specimens.