Children who are very thin but have a big stomach may be caused by physiological factors such as eating too much gas-producing food or eating inappropriately, or it may be caused by other reasons such as indigestion and cirrhosis of the liver. 1. Physiological factors: If a very thin child eats too much soy, radish, onion and other easy to produce gas food may lead to gastrointestinal flatulence, resulting in the performance of a large stomach. In addition, very thin children eat too fast or talk while eating, will swallow too much air, will also make the stomach bigger. 2. Dyspepsia: Dyspepsia may be caused by gastrointestinal dyskinesia, Helicobacter pylori infection, and decreased diastolic function of the stomach to food tolerance. Patients will have postprandial fullness, early satiety, abdominal pain and other manifestations. If the child is very thin and has indigestion, it is easy to have abdominal distension and thus have the symptom of a big stomach. 3. Cirrhosis: Cirrhosis is considered to be caused by viral hepatitis and long-term cholestasis. The patient will have weakness, loss of appetite, spider nevus, ascites, weight loss, jaundice and other symptoms, so the child will appear very thin but the performance of the stomach. The child is very thin but the stomach may also have other causes, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment.