Severe rectal anastomotic stenosis can not only cause intestinal obstruction, but also be accompanied by frequent defecation, which affects the quality of life, and patients face the outcome of permanent stoma or temporary stoma again. Traditional transabdominal resection and reconstruction of rectal anastomotic stenosis is more likely to occur due to unclear anatomical structure, dense scars around the intestinal canal, complications such as ureteral and urethral injury and massive presacral hemorrhage. In addition,41%of patients with anastomotic stenosis who underwent reoperation through abdominal surgery had anastomotic leakage again, and up to 30% of patients could not close the stoma. The advantages of transanal total mesorectal excision (taTME) using a transanal approach for total mesorectal excision in the treatment of middle and low rectal cancer with difficult pelvis have been demonstrated by our group. However, taTME has rarely been explored in the treatment of anastomotic stenosis. Our team retrospectively summarized the patients who underwent transabdominal transanal endoscopic resection and reconstruction of anastomotic stenosis (l-taTME), and initially demonstrated the safety and effectiveness of this surgical method, with a stoma closure rate of 90%. Although the advantages of l-taTME in the treatment of severe rectal anastomotic stenosis are obvious in theory and preliminary clinical practice, there is a lack of prospective studies. Therefore, the investigators plan to conduct a prospective clinical study to observe the safety and efficacy of l-taTME reconstruction surgery, and to provide high-level evidence-based medical basis for the selection of resection and reconstruction surgery for patients with rectal anastomotic stenosis.