Neoadjuvant chemotherapy refers to adjuvant chemotherapy given prior to surgery. The use of neoadjuvant chemotherapy stems from several problems: some patients are found to be unresectable by surgical exploration, mainly because the tumor is too large or invades adjacent organs; postoperative chemotherapy for gastric cancer is somewhat blind, and the drug is only known to be ineffective after the tumor recurs. Theoretically, neoadjuvant chemotherapy has the following advantages: 1. to prevent the change of tumor blood supply after surgery from affecting the chemotherapy effect; 2. to prevent resection of primary tumor from stimulating the growth of remaining tumor; 3. to make tumor down-stage and improve tumor resection rate; 4. to reduce intraoperative dissemination and eliminate potential micro-metastases; 5. chemotherapy sensitivity experiment to understand the sensitivity of tumor to chemotherapy drugs and reasonably select sensitive drugs; 6. to eliminate Patients who are not suitable for surgical treatment. The duration of adjuvant chemotherapy given before surgery should not be too long, usually given for 2-3 months. Its mechanism of action is different from the 6-12 courses of adjuvant chemotherapy after surgery, so it is not called preoperative adjuvant chemotherapy, but neoadjuvant chemotherapy or induction chemotherapy. The increasing use of neoadjuvant chemotherapy for gastric cancer is also related to the current chemotherapeutic drugs with good efficacy and significantly lower toxic side effects. Clinical studies conducted in UK patients have also confirmed the contribution of neoadjuvant chemotherapy to the long-term survival of gastric cancer patients.