Residual gastric cancer refers to the first primary carcinoma that occurs in the residual stomach more than 5 years after major gastrectomy for benign gastric lesions, or the second primary carcinoma that occurs in the residual stomach more than 15-20 years after gastric cancer surgery. Residual gastric cancer can occur in any part of the residual stomach, with the anastomosis being the most common, followed by the less curved side of the residual stomach and the cardia. The clinical manifestations of remnant gastric cancer are as follows: The clinical manifestations of remnant gastric cancer are similar to those of general gastric cancer, mainly manifesting as vague pain in the upper abdomen, epigastric fullness after eating, loss of appetite, emaciation, anemia, weakness, symptoms of obstruction in the cardia or anastomosis, black stool or persistent positive fecal occult blood test. Residual gastric cancer is easily misdiagnosed as anastomotic ulcer and delayed treatment. Most of the anastomotic ulcers are within 3 years after surgery, while residual gastric cancer is more than 10 years after surgery. Therefore, whenever a long period of time after gastric surgery passes well, and the symptoms of upper abdomen newly appear, residual gastric cancer should be suspected and gastrointestinal imaging and gastroscopy should be performed as early as possible.