Assess the Efficacy of Radiotherapy and Sequential Chemotherapy and AK104 Before TME Surgery for Local CRC（AK104-IIT-13）

Inclusion Criteria: * 1\. Age 18-75 years old, gender is not limited; * 2\. Stage II/III under MRI or endoscopic ultrasound ; * 3\. Fiber colonoscopy or diagnosis examination, the lower boundary of the lesion is 15m ≤ from the margin; * 4\. Rectal adenocarcinoma confirmed or revisited by pathology; * 5\. Karl Fischer score ≥ 80 points or ECOG score of 0-1; * 6\. Meet the following laboratory diagnostic indicators: hemoglobin ≥ 100g/L, white blood cell ≥ 3.5×109/L; neutrophils≥ 1.5×109/L, platelet ≥ 100×109/L; creatinine ≤ 1.0× upper limit of normal (UNL), urea nitrogen (BUN) ≤ 1.0× upper limit of normal (UNL); Alanine aminotransferase (ALT) ≤1.5× upper limit of normal (UNL); Aspartate aminotransferase (AST) ≤1.5× upper limit of normal (UNL); Alkaline phosphatase (ALP) ≤1.5× upper limit of normal (UNL); Total bilirubin (TBIL) ≤ 1.5× upper limit of normal (UNL); urine protein (-); Clotting time is normal. * 7\. No history of allergy to 5-Fu drugs, no history of allergy to platinum drugs; * 8\. With primary rectal cancer required to undergo surgery (except palliative ostomy), chemotherapy or other anti-tumor therapy before diagnosis to enrollment; * 9\. Not received radiation before; * 10\. Sign the informed consent form. Exclusion Criteria: * 1\. Previous anti-PD-1/L1 and anti-CTLA-4 immune drugs or other immunoassay drugs; * 2\. With severe autoimmune diseases: active inflammatory bowel disease (including Crohn's disease, ulcerative colitis), rheumatoid arthritis, scleroder…