Unexplained ascites may be caused by acute peritonitis, malignant tumor of abdominal organs, etc. It can be diagnosed according to clinical manifestations, enteroscopy, laboratory examination and imaging examination. 1. Acute peritonitis: hemorrhagic exudative peritonitis, spontaneous peritonitis, rupture of ectopic pregnancy, rupture of hepatic hemangioma, etc. can induce ascites, which can be diagnosed according to the patient’s manifestations of acute blood loss such as accompanied by fever, pallor, cold and clammy skin, shortness of breath, etc., combined with the abdominal ultrasonography and other imaging tests and hemoglobin and other laboratory tests. 2. Malignant tumor of abdominal organs: (1) Gastric cancer: it can be accompanied by upper gastrointestinal symptoms such as epigastric pain, poor appetite, anorexia, nausea, vomiting, etc. Aided by gastroscopy and biopsy, the diagnosis can be confirmed. (2) Intestinal cancer: it can be accompanied by lower gastrointestinal symptoms such as abdominal mass, rectal mass, change of bowel habit (diarrhea, constipation, etc.) and fecal symptom (mucus stool, pus and blood stool, etc.), and abdominal pain, etc. Auxiliary colonoscopy, laboratory tests such as tumor marker and imaging tests such as abdominal ultrasound and CT can lead to a clear diagnosis. Unexplained ascites, it is recommended to consult a doctor in time to clarify the diagnosis, under the guidance of the doctor to carry out targeted treatment.