Inclusion Criteria:  The age is ≥18 years old and <75 years old. Eastern Cooperative Oncology Group (ECOG) physical status is 0 or 1. Untreated and histologically confirmed squamous cell lung carcinoma. Potentially operable stage IIIA-IIIB (N2) squamous cell lung carcinoma on enrollment (as defined by the American Joint Committee on Cancer 8th Edition). Sufficient pre-treatment tumor tissue samples/peripheral blood samples for biomarker analysis. Sufficient organ functions, including: Haematological status: absolute neutrophil count(ANC) ≥1.5×10^9 /L, platelet count(PLT) ≥100×10^9 /L, hemoglobin(HB) ≥90 g/L; Liver function: alanine glutamate transaminase (ALT) and glutamate transaminase (AST) ≤2.5 x upper limit of normal range (ULN), total bilirubin (TBIL)≤1.5 x upper limit of normal range (ULN); Kidney function: Creatinine(Cr)≤1.5 x upper limit of normal range(ULN) or Creatinine clearance ≥45 ml/min (calculated according to Cockcroft-Gault equation)  Exclusion Criteria:  Participants with known EGFR, ALK or ROS1 sensitive mutations. Participants with autoimmune diseases, tuberculosis, active hepatitis or HIV. Participants who are not expected to tolerate surgery, such as patients with cardiopulmonary insufficiency, etc. A history of other malignant tumors in the past 5 years, except for cured cervical carcinoma in situ, cured basal cell carcinoma of the skin and superficial bladder cancer [Ta, Tis & T1]. Participants who have used PD-1/PD-L1 and other immunotherapy drugs before. Women of childbearing age as the exclusion criteria.