Inclusion Criteria:  Histologically confirmed stage IIIA Non-Small Cell Lung Cancer without ALK，EGFR or ROS1 sensitive mutation Be willing and able to provide written informed consent/assent for the trial Have measurable or unmeasurable disease based on RECIST 1.1. Be willing to provide archival tissue from a tumor lesion or obtain a new biopsy if tissue unavailable.  Have a performance status of 0 or 1 on the Eastern Cooperative Oncology group (ECOG) Performance Scale.  Demonstrate adequate organ function Absolute neutrophil count (ANC) ≥1,500/mcL Platelets ≥100,000 / mcL Hemoglobin ≥9 g/dL or ≥5.6 mmol/L without transfusion or erythropoiesis dependency Serum creatinine or Measured or calculated creatinine clearance ≤1.5 X upper limit of normal (ULN) or ≥60 mL/min for subject with creatinine levels > 1.5 X institutional ULN Serum total bilirubin ≤ 1.5 X ULN, or Direct bilirubin ≤ ULN for subjects with total bilirubin levels > 1.5 ULN Aspartate transaminase (AST) (SGOT) and Alanine transaminase (ALT) (SGPT) ≤ 2.5 X ULN or ≤ 5 X ULN for subjects with liver metastases Albumin ≥2.5 mg/dL International Normalized Ratio (INR) or Prothrombin Time (PT) ≤1.5 X ULN unless subject is receiving anticoagulant therapy as long as PT or partial thromboplastin time (PTT) is within therapeutic range of intended use of anticoagulants ≤1.5 X ULN unless subject is receiving anticoagulant therapy as long as PT or PTT is within therapeutic range of intended use of anticoagulants Female subject of childbearing potential should have a negative urine or serum pregnancy within 72 hours prior to receiving the first dose of study medication. If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required Female subjects of childbearing potential should be willing to use 2 methods of birth control or be surgically sterile, or abstain from heterosexual activity for the course of the study through 120 days after the last dose of study medication. Subjects of childbearing potential are those who have not been surgically sterilized or have not been free from menses for > 1 year Male subjects should agree to use an adequate method of contraception starting with the first dose of study therapy through 120 days after the last dose of study therapy  Exclusion Criteria:  Presence of locally advanced, inoperable or metastatic disease Is currently participating and receiving study therapy or has participated in a study of an investigational agent and received study therapy or used an investigational device within 4 weeks of the first dose of treatment Has a diagnosis of immunodeficiency or is receiving systemic steroid therapy or any other form of immunosuppressive therapy within 7 days prior to the first dose of trial treatment Has a known history of active Bacillus Tuberculosis (TB) Hypersensitivity to Sintilimab or any of its excipients. Has had any prior chemotherapy, targeted small molecule therapy, or radiation therapy for the currently diagnosed cancer.  Has a known additional malignancy that is progressing or requires active treatment. Exceptions include basal cell carcinoma of the skin or squamous cell carcinoma of the skin that has undergone potentially curative therapy or in situ cervical cancer.  Has active autoimmune disease that has required systemic treatment in the past 2 years (i.e. with use of disease modifying agents, corticosteroids or immunosuppressive drugs). Replacement therapy (eg., thyroxine, insulin, or physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency, etc.) is not considered a form of systemic treatment.  Has known history of, or any evidence of active, non-infectious pneumonitis. Has an active infection requiring systemic therapy. Has a history or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the trial, interfere with the subject's participation for the full duration of the trial, or is not in the best interest of the subject to participate, in the opinion of the treating investigator.  Has known psychiatric or substance abuse disorders that would interfere with cooperation with the requirements of the trial.  Is pregnant or breastfeeding, or expecting to conceive or father children within the projected duration of the trial, starting with the pre-screening or screening visit through 120 days after the last dose of trial treatment.  Has received prior therapy with an anti-PD-1, anti-PD-L1, or anti-PD-L2 agent. Has a known history of Human Immunodeficiency Virus (HIV) (HIV 1/2 antibodies). Has known active Hepatitis B (e.g., HBsAg reactive) or Hepatitis C. Has received a live vaccine within 30 days of planned start of study therapy.