1, unclean diet, or over-eating spicy, and too little fiber in food, the gastrointestinal tract can not produce effective stimulation, gastrointestinal peristalsis slowed, resulting in constipation. 2, the gastrointestinal tract obstruction, its contents can not be normal through the stomach or intestinal tract constipation, such as pyloric obstruction, intestinal obstruction, in which the elderly pay special attention to tumor-induced obstruction or stenosis resulting in constipation. 3, the colon stress function is reduced. Under normal circumstances, the contents of the colon can stimulate the colon to cause peristalsis, when the colon, especially the rectum stress decreases, although the stool into the rectum can not cause bowel movements and defecation. It is common for the elderly to take oral laxatives for a long period of time, or for young people to be nervous at work and suddenly see the need to defecate. In addition, hyperthyroidism and high blood calcium can also cause constipation. 4, when there are anal diseases such as anal fissure, hemorrhoids, abscess around the anus, etc., because of the painful defecation, and do not dare to defecate caused by constipation, also known as defecation difficulties. 5, mental factors, excessive nervousness or depression, inhibit the natural defecation reflex, can produce and develop into serious constipation. 6, some extra-intestinal diseases can also cause constipation, such as: hypokalemia, hypothyroidism, paroxysmal disease, etc. 7, long-term oral administration of some drugs can also produce constipation, such as gastric mucosa protectors: Similac, Lizudra, etc., and hypotensive drugs such as calcium ion antagonists. When constipation occurs, pay attention to further examination of blood, stool regularity plus occult blood, and thyroid function, in addition to gastrointestinal motility test, fecal imaging or colonoscopy.