The clinical staging of gastric cancer includes four stages, stages I and II belong to the early stage of gastric cancer, stage III belongs to the middle stage of gastric cancer, and stage IV belongs to the late stage of gastric cancer. It is usually believed that the cancer cells of early gastric cancer patients are confined to the mucosal and submucosal layers, and the lymphatic metastasis is basically zero. Therefore, minimally invasive resection can be performed through endoscopy to achieve the purpose of radical cure; when progressing to advanced gastric cancer, it is considered to have invaded through the submucosal layer and reached deep into the muscular layer with distant metastasis. For example, metastasis of lymph nodes, lung metastasis and liver metastasis appear, which can lead to severe wasting symptoms and poor prognosis. The staging method by describing the tumor size, lymph node metastasis and the presence of distant organ metastasis is an effective supplement to the classification method of early, middle and late stage of gastric cancer, namely TNM staging. t represents the primary tumor condition and is divided into T1, T2, T3, T4; N represents the scope of regional lymph node metastasis and can be divided into N1, N2, N3; M represents distant metastasis and is divided into M1, M1A, M1B, M1A, M1B. The two classification methods need to be used in conjunction with each other to better describe the seriousness of gastric cancer.