The causes of thoracoabdominal effusion are the following: i. Liver dysfunction and insufficient synthesis of albumin by the liver, resulting in hypoproteinemia, which causes thoracoabdominal effusion. Second, protein loss caused by nephrotic syndrome, resulting in hypoproteinemia, which causes thoracoabdominal effusion. Third, due to abdominal and thoracic vein obstruction thrombosis situation, resulting in impaired blood return, elevated venous pressure, and fluid components in the blood even to the thoracoabdominal cavity, causing thoracoabdominal effusion. Fourth, cardiac insufficiency, due to cardiac insufficiency, can not pump blood to the lungs in a timely manner, resulting in blood stagnation in the surrounding tissues, thus causing thoracoabdominal effusion. Fifth, thoracoabdominal effusion caused by hypoproteinemia, long-term poor nutritional feeding, resulting in low protein can cause thoracoabdominal effusion. Sixth, thoracoabdominal tumors can lead to low protein caused by thoracoabdominal effusion, can check the abdominal or thoracic fluid, visible tumor cells.