Inclusion Criteria:  Age 18-75y, male or female; 2. Patients with gastric adenocarcinoma or gastroesophageal junction adenocarcinoma confirmed by histology or cytology; 3. Patients with stage III gastric adenocarcinoma or gastroesophageal junction adenocarcinoma who have not received any antitumor therapy besides surgery; 4. ECOG score: 0 ~ 1; 5. Expected survival ≥12 weeks; 6. The main organs function are well, and the laboratory test data meets the following standards: (1) Blood routine: neutrophil absolute count ≥1.5×109/L (or greater than the lower limit of laboratory normal value in the research center), platelet count ≥100×109/L, hemoglobin ≥90g/L; (2) Liver function: serum total bilirubin ≤1.5 times the upper limit of standard value (ULN), AST and ALT≤2.5 times ULN, and ≤5 times ULN if liver metastasis exists; (3) Renal function: CrCl≥ 60mL /min/1.73m2 (calculated according to the Cockcroft-Gault formula); 7. Female subjects with the fertility, as well as the partner of male subjects with the fertility, need to use an approved medical contraception (such as intrauterine device, the pill or condoms) during the research and at least 6 months from the last treatment of camrelizumab or chemotherapy; 8. HER2 negative, volunteering to provide tumor tissue samples after surgery and adjuvant therapy; 9. Voluntarily participated in the study and signed informed consent with good compliance and follow-up.  Exclusion Criteria:  History of gastrointestinal perforation and/or fistula within 6 months prior to first medication; 2. Uncontrolled pleural effusion, pericardial effusion or peritoneal effusion requiring repeated drainage; 3. Allergic to carrelizumab, oxaliplatin, or tegio; 4. Received any of the following treatments: a. Enrolled in another clinical study at the same time; b. Prior to initial use of the study drug, antitumor therapy (including radiotherapy, chemotherapy, immunotherapy, endocrine therapy, targeted therapy, biotherapy, or tumor embolization, etc.) was performed; c. Subjects requiring corticosteroids (> 10mg prednisone equivalent daily dose) within 2 weeks prior to initial use of the study drug. Other special situations require communication with the researcher. In the absence of active autoimmune disease, inhaled or topical steroids and adrenocorticosteroid replacement at doses > 10mg/d of prednisone efficacy are permitted; d. Those who have received antitumor vaccine or have received live vaccine within 4 weeks prior to the first administration of the study drug; e. Major surgery or severe trauma within 4 weeks prior to first use of the study drug; 5. Patients with central nervous system metastasis; 6. Have active autoimmune diseases or a history of autoimmune diseases (such as interstitial pneumonia, colitis, hepatitis, hypophysitis, vasculitis, nephritis, hyperthyroidism, hypothyroidism, including but not limited to the above diseases or syndromes); Except for patients with epilepsy or recovered childhood asthma/allergy without any intervention as adults; Autoimmune mediated hypothyroidism treated with stable doses of thyroid replacement hormone; Type 1 diabetes with a steady dose of insulin; 7. Have a history of immunodeficiency, including HIV positive, or other acquired or congenital immunodeficiency diseases, or a history of organ transplantation and allogeneic bone marrow transplantation, or active hepatitis (hepatitis b: HBV-dna test value over 500IU/ml or 2500 copies /ml); 8. The subject has cardiovascular clinical symptoms or diseases that are not well controlled, including but not limited to: e.g. : (1) NYHA class II or higher heart failure; (2) unstable angina; (3) myocardial infarction occurred within 1 year; (4) Clinically significant supraventricular or ventricular arrhythmias are still poorly controlled without or after clinical intervention; 9. Severe infection (CTCAE5.0 > 2) occurred within 4 weeks prior to the first use of the study drug, such as severe pneumonia, bacteremia, and infection complications requiring hospitalization; Baseline chest imaging suggests active lung inflammation, signs and symptoms of infection within 2 weeks prior to initial use of the study drug, or the need for oral or intravenous antibiotic treatment, except for prophylactic use of antibiotics; 10. A history of interstitial lung disease (excluding radiation pneumonia or non-infectious pneumonia without hormone therapy); 11. Patients with active tuberculosis infection found by history or CT examination, or patients with active tuberculosis infection history within 1 year before enrollment, or patients with active tuberculosis infection history more than 1 year ago but without formal treatment;12. Diagnosis of any other malignancy, other than malignancies with a low risk of metastasis and death (5-year survival > 90%), such as adequately treated basal cell or squamous cell skin cancer or carcinoma in situ of the cervix, within 5 years prior to first use of the study drug; 13. Pregnant or lactating women; 14. In the judgment of the investigator, the subject has other factors that may cause him/her to be forced to terminate the study, such as other serious diseases (including mental illness) requiring combined treatment, seriously abnormal laboratory test values, family or social factors that may affect the safety of the subject or the collection of test data; 15. According to the investigator's judgment, subjects have other factors that may cause them to be forced to terminate the study, such as other serious diseases (including mental illness) requiring combined treatment, seriously abnormal laboratory test values, family or social factors that may affect subjects' safety or the collection of test data.