Gastric reduction surgery for obesity and obesity associated disorders and surgery for gastric cancer have many similarities, the most obvious one being that they both require the removal of part of the stomach for treatment purposes, and both require prolonged care after the surgery to avoid complications, and patients can also achieve some weight loss for a period of time after the surgery for gastric cancer. However, from the doctor’s perspective, these two surgeries are very different. Gastric cancer surgery is a kind of treatment when the patient has cancer in the stomach and is in the early stage, and the location of the surgery is determined according to the location of the patient’s cancer. Gastric reduction surgery is specifically used for the treatment of obesity and the various complications caused by obesity, and the surgery is basically fixed. During the surgery, 2-6 cm of gastric sinus above the pylorus is preserved in the direction of the large curve of the stomach, and the large part of the stomach is removed along the long axis of the stomach, so that the residual stomach is “banana-shaped” with a volume of about 60-80 ml, which preserves the completed structure of the stomach and does not affect the normal life too much. Stomach reduction surgery is not comparable to stomach cancer surgery in terms of the nature of the surgery, as stomach cancer surgery is a therapeutic surgery, just like a sickness that needs to be treated, there is also a possibility of recurrence; whereas stomach reduction surgery has a preventive role in addition to treatment. It is more secure than gastric cancer surgery.