The causes of small stools may be related to dietary factors, congenital factors, tumors, etc. can also lead to small stools. 1. Dietary factors: usually eat more fine food, eat less coarse food, eat food containing less dietary fiber, which will lead to fine stools. Patients can eat more coarse grains and foods with high dietary fiber content, and their stools will gradually return to normal. 2. Congenital factors: Congenital narrowing of the intestinal canal, small anal opening, will also have the symptom of thin stool. 3. Tumor: Tumor in anal and intestinal area can lead to narrowing of anus and cause small stool. For people with small stool, it is recommended to consult a doctor in time to clarify the cause and treat it actively. Patients should not use medication by themselves, but should be treated under the guidance of physician’s consultation.