Inclusion Criteria:  At least 18 years of age, 75 years of age or less, no gender limitation; Patients with untreated locally advanced resectable adenocarcinoma of the stomach or gastroesophageal junction, with clear pathological diagnosis; According to RECIST 1.1, the efficacy evaluation standard for solid tumors, there were definite measurable and evaluable lesions, with spiral CT lesions ≥1cm； Physical condition score KPS score 80-100 points ； Able to receive systemic chemotherapy; No obvious active bleeding; No history of other malignancies, except cured carcinoma in situ of the cervix, basal carcinoma of the skin or squamous cell carcinoma; Women of childbearing age had negative pregnancy test and had voluntarily taken effective and reliable contraceptive measures during the clinical trial； Sign the informed consent form voluntarily；  Exclusion Criteria:  There are distant metastasis or local invasion of adjacent organs； Tumor recurrence; Suffered from or had previously suffered from autoimmune diseases; Past organ transplantation or HIV patients; Allergic to 5-fluorouracil, calcium leucoin, oxaliplatin, or irinotecan, or contraindications to 5-fluorouracil, calcium leucoin, oxaliplatin, or irinotecan exist; Malignant secondary disease dating back to 5 years (exceptions: carcinoma in situ of the cervix, adequately treated basal cell carcinoma of the skin)； Severe non-surgical complications or acute infections； Peripheral polyneuropathy>NCI Grad I；  Impaired blood system, liver and kidney function. The evaluation criteria are as follows:  Blood routine: white blood cells (WBC) <3.0×109/L, neutrophils (ANC) <1.5×109/L, platelets (PLT) <100×109/L, hemoglobin (Hb) <90g/L.  Liver and kidney function: total bilirubin (TBIL)>1.5 times the upper limit of the normal value; urea nitrogen (BUN)>1.5 times the upper limit of the normal value；Creatinine (Cr)>1.5 times the upper limit of the normal value；Alanine aminotransferase and aspartate aminotransferase (ALT and AST)> 3 times the upper limit of the normal value (without liver metastasis)；Alanine aminotransferase and aspartate aminotransferase (ALT and AST)> 5 times the upper limit of the normal value (for liver metastases)；  Subjects with symptomatic brain metastases; Subjects with obvious clinical manifestations of arrhythmia, myocardial ischemia, severe atrioventricular block, cardiac insufficiency, and severe valvular disease; Subjects with severe bone marrow failure; Psychotic subjects who are difficult to control； Pregnant or lactating subjects; Subjects whom the investigator considers inappropriate to participate in this trial； Include in another clinical trial；