TNM stage of gastric cancer is used to determine the severity of gastric cancer, whether lymphatic metastasis is present, and whether the tumor invades surrounding organs. According to the different degrees of invasion, the disease can be clearly evaluated and it is also convenient to give targeted treatment plan. t is mainly to see the depth of tumor invasion, with T as the representative of primary tumor, T1 means the tumor invades the optic mucosal layer and submucosal layer, T2 means the tumor invades the base and subplasma layer, T3 means the tumor invasion has penetrated the plasma layer and the disease is aggravated. N stage refers to the metastasis of lymph nodes, N0 means no local lymph nodes metastasis, N1 means less than 7 local lymph nodes metastasis, N2 means more than 7 lymph nodes metastasis and less than 15 lymph nodes metastasis, N3 means more than 15 lymph nodes metastasis, M stage refers to the presence of distant metastasis, M0 means no distant metastasis, M1 means tumor has distant metastasis. M0 means the tumor has no distant metastasis, M1 means the tumor already has distant metastasis.