The sudden appearance of stomach enlargement in stomach cancer patients can be caused by factors such as hypoproteinemia and abdominal metastasis of tumor, which need to be treated according to the causes. Gastric cancer is a common malignant tumor of digestive system caused by Helicobacter pylori infection, bad dietary habits and other factors. With the development of the disease, hypoproteinemia can occur, leading to the symptom of ascites. At this time, the symptoms of ascites can be alleviated through the infusion of albumin, peritoneal puncture extraction of ascites and other methods. In addition, when peritoneal or abdominal organs metastasis occurs, it can also lead to malignant ascites. At this time, primary and metastatic lesions can be treated by radiotherapy, targeted therapy, immunotherapy, and peritoneal perfusion. Symptomatic treatment is also feasible, such as taking furosemide and other diuretics as prescribed by the doctor; ascites extraction and so on. It is recommended to actively consult a doctor to clarify the cause of the disease and carry out targeted treatment.