Postoperative adjuvant chemotherapy for gastric cancer is started when the patient’s physical condition basically returns to normal after surgery, usually four weeks after surgery, with special attention to the patient’s need to recover from postoperative feeding and the need for remission of perioperative complications before adjuvant chemotherapy is administered. The conditions suitable for adjuvant chemotherapy are patients with pathological stage II or III after D2 radical surgery, and adjuvant chemotherapy is not recommended for stage IA; there is no sufficient medical evidence on whether adjuvant chemotherapy is needed for stage IB gastric cancer, but patients with positive lymph nodes can be considered for adjuvant chemotherapy; patients less than 40 years old with histological hypofractionation and factors such as neurological or vascular and lymphatic infiltration are recommended for adjuvant chemotherapy. Single agent chemotherapy is generally used and may reduce recurrence. Combination chemotherapy is completed within six months, and single-agent chemotherapy should not be administered for more than one year. Adjuvant chemotherapy regimens recommend combination chemotherapy with fluorouracil-based drugs combined with platinum-based drugs. For patients with poor physical status and advanced age who cannot tolerate a two-drug regimen of chemotherapy, single-agent chemotherapy with oral fluorouracil analogs is generally considered.