Most scholars believe that cancer occurring in the residual stomach more than 5 years after major gastrectomy for benign gastric lesions and more than 10 years after radical resection for gastric cancer can be defined as residual gastric cancer. Ultrasound endoscopy, as a unification of endoscopy and ultrasound instrument, avoids the problem of gas in the gastrointestinal tract interfering with ultrasound on the body surface, and is the main staging tool for gastrointestinal tumors. It can clearly display the 5-layer structure of gastric wall, and the accuracy rate of T-staging for early gastric cancer is 70%-80%; the average accuracy rate of T-staging for progressive gastric cancer is over 80%, and the accuracy rate of N-staging for perigastric lymph node metastasis at the first and second stations is 60-70%. In the UICC 2001 version of TNM staging of gastric cancer, the criteria for defining the number of metastatic lymph nodes were used. In this study, we determined that the endoscopic ultrasound image criteria for metastatic lymph nodes were oval or round, hypoechoic, with clear borders, poorly demarcated corticomedullary lymph nodes, and maximum diameter greater than 1 cm, but it should be noted that preoperative staging in combination with enhanced abdominal CT was essential. In comparing the cases of postoperative residual gastric cancer after benign lesion and postoperative residual gastric neoplastic cancer after gastric cancer, it can be found that the lymph node metastasis of postoperative residual gastric cancer after benign lesion is similar to proximal gastric cancer regardless of whether the lesion is located in the gastric body, cardia or gastrointestinal anastomosis, and is concentrated in the root of the left gastric artery, splenic hilum and splenic artery trunk area; whereas the total number of lymph nodes of postoperative residual gastric neoplastic cancer after gastric cancer is less and the metastasis is less regular. The reason for this may be that the major gastrectomy for benign lesions only dealt with blood vessels, without clearing the perigastric lymph nodes, so the lymph of the lesions at the cardia, gastric body and anastomosis can flow back through the left gastric artery, short gastric artery and left gastric omental artery area, resulting in lymph node metastasis of proximal gastric cancer]. However, when the first surgery is radical gastric cancer, extensive lymph node dissection has been performed, resulting in obstruction of lymphatic return, occurrence of metastasis through the traffic branch or upstream, such as metastasis to the paraoesophageal lymph nodes in the lower thoracic segment. Patients with remnant stomach should undergo regular gastroscopy to avoid the first symptoms appearing when the disease is already late in its course. Nowadays, the use of a large number of PPI drugs has drastically reduced the number of patients undergoing major distal gastrectomy, but due to the increase in the detection rate of early gastric cancer, the promotion of surgical standardization and the development of systemic chemotherapy, the number of patients with radical gastric cancer has increased; it is possible that the number of patients with de novo cancer of the remnant stomach after gastric cancer surgery will increase, so these patients should be closely followed up and urged to undergo regular gastroscopy to give them a chance of early diagnosis and treatment. In conclusion, the diagnostic accuracy of ultrasound endoscopy in TN staging of remnant gastric cancer is high. In view of its non-invasive, reproducible and easy to promote characteristics, it can be used in preoperative staging and surgical resectability evaluation of residual gastric cancer; however, because of its poor specificity for metastatic lymph nodes and limited scanning range, it must be combined with surgical staging methods such as abdominal CT.