Rectal cancer is cancer between the dentate line and the junction of the rectosigmoid colon, and is one of the most common malignant tumors of the gastrointestinal tract. The location of rectal cancer is low, so it can be easily diagnosed by rectal finger diagnosis and sigmoidoscopy. However, because of its location deep into the pelvic cavity and complex anatomical relationship, surgery is not easy to be complete and the recurrence rate after surgery is high. The proximity of lower and middle rectal cancer to the anal sphincter makes it difficult to preserve the anus and its function during surgery, which is a difficult problem in surgery and is also the most debated disease in terms of surgical methods. The median age of rectal cancer incidence in China is around 45 years old. The incidence rate of young people has a tendency to increase. High-incidence group of rectal cancer 1.Patients older than 30 years old with change in bowel habits and stool properties; 2.Patients with rectal adenoma and chronic inflammation of the rectum; 3.Patients with family history of colorectal cancer or history of breast cancer, ovarian cancer and endometrial cancer; 4.Patients with family history of polyps and history of pelvic radiotherapy.