According to the latest version of AJCC TNM staging of gastric cancer, gastric cancer T4aN3M0 is clinical stage III, which belongs to the progressive gastric cancer and mostly requires comprehensive treatment. In the description of gastric cancer T4aN3M0, T4a means that the tumor has invaded the lamina propria, the mucosal muscularis layer, infiltrated and penetrated the subplasma connective tissue, and invaded to the visceral peritoneum, N3 means that there are more than 7 regional lymph node metastases, and M0 means that there is no distant metastasis. Gastric cancer T4aN3M0 belongs to clinical staging stage III, which can be assisted by CT, ultrasound endoscopy and other examinations for TNM staging. For advanced gastric cancer with clinical stage III, if there are no contraindications to surgery, such as poor general condition and poor relationship between tumor and surrounding tissues, the comprehensive treatment of “preoperative neoadjuvant therapy + surgery + postoperative adjuvant therapy” is often adopted. Preoperative neoadjuvant chemotherapy can help to shrink the tumor and increase the surgical resection rate. Relevant tests can also be conducted actively to advocate targeted or immunotherapy. In conclusion, if you have T4aN3M0 gastric cancer, it is recommended to consult the doctor in time and accept treatment actively to improve the quality of life and prolong the life span.