With the continuous progress of surgical technology, more and more rectal cancer patients have realized anal preservation, achieving both long-term efficacy and quality of life. However, there are often feedbacks from patients that after anal preservation surgery for low rectal cancer, there are a series of defecation-related intestinal function alterations such as increased stool frequency, frequent urge to defecate, urgency to defecate, difficulty in defecation, incontinence and even fecal incontinence, etc. Though most of the patients are able to get different degrees of improvement as the postoperative time passes, it still affects the daily life of the patients seriously. According to statistics, up to 90% of postoperative rectal cancer patients will have different degrees of defecation abnormality, among which the serious patients can reach 30%. In fact, these defecation dysfunctions mentioned above are medically called low anterior resection syndrome (LARS) after rectal cancer surgery. I. What are the causes of occurrence? 1.Age factor: with the decline of anal function with age, especially in elderly women older than 75 years old, the percentage of defecation dysfunction occurring after rectal surgery is high. 2, anatomical changes: one of the main physiological functions of the rectum is to store feces. After rectal resection surgery, a section of intestinal tube needs to be removed, resulting in a decrease in the storage function of the remaining rectum and a corresponding increase in the number of bowel movements. Generally speaking, the closer the tumor is to the anus, the higher the percentage of post-surgical defecation dysfunction. 3. Dysfunction of internal anal sphincter: after ultra-low rectal resection, patients need to remove part of internal anal sphincter and its innervating nerves, which leads to passive anal defecation or fecal incontinence. 4, anal canal defecation sensory dysfunction: rectal dentate line is located in the rectum and anal canal between a demarcation line, generally about 2.5cm from the anus, in defecation has an important significance. Hypospadias is related to the distance of anastomosis from the dentate line. The closer the operation is to the dentate line, the more likely it is to cause sensory damage to the anal canal and reduce the sensitivity of the anal canal, which results in frequent urge to defecate and fecal incontinence. 5, preoperative radiotherapy: there is evidence that patients who receive preoperative radiotherapy have more serious defecation dysfunction after rectal surgical resection. 6, anastomotic problems: such as anastomosis, anastomotic scar, anastomotic stenosis, or even anastomotic fistula. 7, psychological factors: some patients have postoperative defecation fear and psychological disorder. Second, how long does it take for the abnormal defecation to get better? Most patients with abnormal defecation function will get some degree of improvement within 1-2 years after surgery. Overall, the symptoms can be gradually reduced with time. However, there are still a few patients who have consistently severe symptoms that seriously affect their quality of life and may eventually opt for permanent colostomy surgery. C. How are bowel abnormalities treated? There are not many choices of treatment options for defecation disorders after rectal surgery, and there is no fixed best option. The daily treatment we can do mainly includes: 1, always keep a positive and good attitude, because nervous and anxious mood will aggravate the bowel abnormality. 2, make adjustments to diet and living habits, such as: eat more fruits and vegetables rich in dietary fiber, and try to eat less food that stimulates the gastrointestinal tract, such as cold, greasy, spicy stimulation, indigestible, easy to produce gas. Appropriate participation in sports, enhance physical fitness. For increased defecation can be oral inhibition of intestinal peristalsis (loperamide), adsorbent antidiarrheal agent (montelukast) and antispasmodic drugs (scopolamine). 3, strengthen the anal function exercise, practice active contraction anal work. Usually two weeks after the operation can start the anal function exercise, increase the function of the anal department muscles. Specific practice references are as follows: a. Chest and knee lying method: kneeling on the bed with both knees, chest to the bed, raise the buttocks, inhale the anal contraction inwardly lifting, exhale and relax for 3-5 seconds, and insist on doing multiple sets of cyclic work every day. b. supine buttock lifting method: lie flat on the bed, legs propped up, with the head, heels as a support point, lift the buttocks, with inhalation, exhalation, regular upward lifting of the anus, clamping the perineum and anus and the surrounding muscles, the patient contraction of the anus and the perineum for 5 seconds, and then 5 seconds of diastasis, several times a day, 5-10 minutes each time. c. When lying down or standing up to tighten the abdomen and buttocks, deep breathing when sitting, close the anal canal for 5 seconds, and then relax, several times a day. Through a long time training can let the patient can form the conditioned reflex defecation habit, and gradually restore the good defecation function. 4, warm water sitz bath to reduce local inflammation, reduce anal irritation and pain. Fiber and intestinal probiotics class of Chinese medicine conditioning. 5.Comprehensive rehabilitation exercise: including pelvic floor muscle training, rectal balloon training, biofeedback training. After a long time of exercise to form a conditioned reflex, to enhance the patient’s ability to control defecation. Part of the program has not been widely carried out in China. 6.Other treatments: transanal enema, acupuncture and moxibustion, sacral nerve stimulation, etc. These need to consult with specialists. In conclusion, it is common to have abnormal defecation at a certain time after anal preservation surgery for rectal cancer, which involves a variety of preoperative, intraoperative and postoperative factors. Patients should keep a good state of mind, avoid negative emotions of anxiety, tension and depression, and actively cooperate with rehabilitation treatment. Thus, patients can have a better quality of long-term survival while undergoing anal preservation surgery.