In this study, the investigators will compare the clinical outcomes of the natural orifice specimen extraction surgery versus traditional robotic-assisted surgery in the treatment of colorectal cancer.

Based on investigators' experience, compared to robotic-assisted colorectal cancer radical resection, robotic colorectal cancer radical resection with natural orifice extraction has more advantages in postoperative stress response, postoperative pain, postoperative recovery and postoperative abdominal aesthetics. However, in terms of tumor radicality, there may be no obvious differences. There are no randomized controlled trails to discuss these questions.This research is based on the above conditions. Investigators use prospective randomized controlled trial to analyze the surgical data, postoperative complications, postoperative recovery of the robotic colorectal cancer radical resection with natural orifice extraction and conventional robotic-assisted colorectal cancer radical resection in order to summarize clinical experience and explore the advantages and disadvantages of robotic colorectal cancer radical resection with natural orifice specimen extraction and to provide a new direction for the surgical treatment of colorectal cancer, which is beneficial to the promotion of NOSES(Natural Orifice Specimen Extraction Surgery ) technology and treatment of colorectal cancer.

Inclusion Criteria:

1. Age ≥ 18 and ≤ 80 years;
2. Performance status of 0 or 1 on ECOG (Eastern Cooperative Oncology Group) scale;
3. Histological or cytological confirmation of colorectal adenocarcinoma;
4. High rectal and sigmoid cancer with the lower margin of the tumor greater than 10 cm from the anal dentate line;
5. T1-3N0M0 at preoperative evaluation according to the American Joint Committee on Cancer (AJCC) Cancer Staging Manual 8th Edition, Transvaginal NOSES procedure w specimen with a circumferential diameter of <5 cm;
6. Preoperative examination did not suggest distant metastasis, implantation or invasion of adjacent organs;
7. Cardiopulmonary liver and kidney function can withstand surgery;
8. Written informed consent for participation in the trial.

Exclusion Criteria:

1. Not suitable for robot laparoscopic surgery;
2. The tumor is too large to be pulled out through the anus or vagina;
3. Simultaneous multiple primary cancer;
4. Emergency surgery due to complication (bleeding, obstruction or perforation) caused by primary cancer
5. Women with acute gynecological infections, vaginal deformities, unmarried and infertile women and women who are married and plan to get pregnant.