Stereotactic Body Radiotherapy Followed by Tislelizumab Plus Platinum-based Chemotherapy Versus Tislelizumab Plus Platinum-based Chemotherapy as Neoadjuvant Therapy in Patients With Resectable Stage Ⅱ-Ⅲ Non-small Cell Lung Cancer: A Phase Ⅲ, Randomized, Multicenter, Prospective Study

Inclusion Criteria:

* 1\. Patients voluntarily agree to participate and sign the informed consent; 2. Patients with cytologically/histologically diagnosed (by means of percutaneous lung aspiration biopsy, bronchoscopy, mediastinoscopy, etc.), untreated stage IIa-IIIa (according to the AJCC 8th edition of thoracic tumor staging) non-small cell lung cancer. In addition, patients with potentially resectable stage IIIb (T3-4N2) NSCLC will also be enrolled. All patients are required to receive PET/CT (or chest + upper abdominal CT + brain MRI) at baseline for clinical staging; 3. Pulmonary lesions will be assessed as resectable/potentially resectable by a multiple disciplinary team including thoracic surgeon; 4. Eastern Cooperative Oncology Group Performance Status 0 to 1 5. Requirements for hematology: i, neutrophils ≥ 1500 x 109/L; ii, platelets ≥ 100 x 109/L; iii, hemoglobin \> 9.0 g/dL; iv, serum creatinine ≤ 1.5 x ULN or creatinine clearance (CrCl) ≥ 40 mL/min; v, aspartate transaminase (AST)/alanine transaminase (ALT) ≤ 3 x ULN; vi, total bilirubin ≤ 1.5 x ULN; vii. forced expiratory volume in the first second (FEV1) ≥ 1.2 L or \> 40% predicted; viii. International Normalized Ratio/activated partial thromboplastin time (INR/APTT) within the normal range; 6. Age 18-75

Exclusion Criteria:

* 1\. Patients with or suspected with autoimmune diseases. Note: patients with vitiligo, type 1 diabetes, hypothyroidism managed with hormone replacement therapy only (Hashimoto's thyroiditis) can be enrolled in the study when there is no clear evidence of recurrence; 2. Patients required systemic corticosteroids treatment (dose \> 10 mg daily prednisolone \[or equivalent\]) or other immunosuppressive drugs within 14 days of enrollment. Note: inhaled or topical corticosteroids, or adrenal replacement therapy (dose \> 10 mg daily prednisolone \[or equivalent\]) are acceptable for patients without apparent autoimmune disease; 3. Historical radiotherapy of chest 4. Active bleeding before treatment 5. Patents with sever heart, lung, liver, or kidney insufficiency 6. Diabetes more than 10-year; unsatisfactory blood glucose control 7. Patients with interstitial lung disease or non-infectious pneumonia 8. EGFR-mutations and ALK-fusion positive NSCLC 9. Patients with other prior malignancies (except skin malignancies other than non-melanoma, and carcinoma in situ at the following sites \[bladder, stomach, colorectal, endometrium, cervix, melanoma, or breast\]) are not eligible for enrollment in this study. However, if the prior malignancies remain in complete response (CR) for ≥ 2 years and no additional anti-cancer therapy is required during the study, such patients are permitted to be enrolled; 10. The patient is medically, psychologically, or physiologically unable to complete the study or to understand the Patient Information Sheet, in the opinion of the investigator; 11. Received prior therapy with an anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CTLA any other drugs specifically targeting T-cell co-stimulation or immunoregulation pathways; 12. Present active hepatitis B or hepatitis C 13. Patients with positive HIV test results or diagnosed with acquired immunodeficiency disease (AIDS); 14. Hypersensitivity to the investigational product; 15. Pregnant or lactating women.