Many patients who have suffered from anal diseases or experienced anal surgery may have a common experience, that is, no matter what the reason, once the anal pain attack, the stool will appear dry and difficult to solve. The author analyzes the causes of constipation mainly from two aspects: 1, psychological factors: due to the patient’s fear of defecation to aggravate anal pain and thus tolerate stool for a long time, resulting in the rectum feces stay too long, too much, excessive absorption of fecal water by the rectum, resulting in fecal hard knots. 2, reflex factors: due to a variety of anal inflammatory stimulation, trauma stimulation (such as postoperative) will cause strong contraction of the anal random muscle (random muscle by These two muscles are stimulated to compress the internal sphincter at the same time and finally cause the muscle tone of the internal sphincter to increase. The internal sphincter is located on the inner side of the external sphincter, and the two muscles are like two movable cannulae that can move up and down within a certain range. The internal sphincter is a continuation of the circular muscle layer of the GI tract and is not under conscious control and has the inherent characteristics of the circular muscle of the GI tract, i.e., it is easily spasticized. When pain is caused by various anal factors, the external sphincter is stimulated to contract first, followed by the contraction of the internal sphincter. If the anal pain-causing factors can disappear quickly, the contraction of the internal and external sphincters will slowly relax; if the anal pain-causing factors (such as inflammation not relieved) still exist, due to the characteristics of the internal sphincter, it will eventually produce spasm and even thickening. At this time, the spasm of the internal sphincter leads to retroreflective dilatation, and the accumulation of stool increases and water is excessively absorbed, which is the cause of constipation due to the loss of relaxation of the internal sphincter.