Middle-aged men with particularly large and hard stomachs may belong to the normal situation, but also may be related to gastrointestinal function decline, cirrhosis of the liver, colorectal tumors and other reasons. 1. Under normal circumstances, due to the increase in age, daily dietary habits and other factors, can lead to a large amount of fat accumulation in the abdomen, the appearance of a particularly large and hard stomach, is a normal physiological phenomenon, it is recommended to improve dietary habits, strengthen the exercise. 2. Gastrointestinal hypoplasia: Gastrointestinal hypoplasia can lead to decreased gastrointestinal peristalsis, intestinal fluid accumulation, gas accumulation, etc., which can also lead to a hard and large stomach. 3. Cirrhosis: Cirrhosis develops to a certain stage, which can lead to the appearance of ascites, manifested as the abdomen becomes bigger, harder and less elastic. 4 Colorectal tumor: it may lead to dilatation of the intestines, increase of gas and fluid in the intestines, resulting in enlargement and hardening of the abdomen. When the above symptoms appear and are accompanied by other discomforts, it is recommended to seek medical treatment in time to clarify the causes under the guidance of specialized physicians.