The causes of flat stools include hemorrhoids, gastrointestinal diseases, and intestinal space-occupying lesions. 1. hemorrhoids: such as internal hemorrhoids attack, will cause the phenomenon of hemorrhoid nucleus enlargement, resulting in stool discharge difficulties, when the stool through the hemorrhoidal parts, can be squeezed, so that the phenomenon of flat stool. 2. Gastrointestinal diseases: If gastroenteritis occurs, it can lead to poor digestion and absorption in the stomach and intestines. When food residue passes through the intestines, the intestines will not be able to fully absorb the water, which will lead to thin stools or shape changes, resulting in flat stools. 3. Intestinal space-occupying lesions: If there are tumors or polyps in the intestines, with the gradual growth of tumors, the intestinal lumen can be compressed, and when the stool passes through this part, it will be squeezed and become flat. When the stool is flat, you should avoid eating foods that are too cold or too hard, spicy and stimulating, so as not to irritate the intestinal tract and aggravate the discomfort. If the stool continues to be flat, it is recommended to go to the hospital in a timely manner, under the guidance of a professional physician to clarify the cause of the disease, and to carry out targeted treatment as soon as possible.