Trial of Robotic Versus Laparoscopic-assisted Radical Resection for Rectal Cancer

Inclusion Criteria: * 1\. Patients who are acceptable to two surgical procedures for the robot- assisted or laparoscopy-assisted rectal cancer, are willing to randomized trial; * 2\. Matching the diagnostic criteria; * 3\. Aged 18-70 years old; * 4\. Preoperative TNM staging (CT, laparoscopic exploration): cT1-3N0-3M0 (excluding M1, T4); * 5\. Preoperative ASA 3 scores; * 6\. There was no history of malignancy, no other malignant tumors by preoperative examination; * 7\. Without undergoing definitive treatment, such as radiotherapy, chemotherapy or immunotherapy preoperatively; * 8\. The informed consent form was signed by the patient himself(herself)or his principal agent; * 9\. In accordance with the international erectile function questionnaire (IIEF) urinary function scale, The urinary sexual function are normal. Exclusion Criteria: * 1\. Age less than 18 years old or more than 70 years old; * 2\. Previous psychiatric patients or patients refused to sign the informed consent; * 3\. Attending other related clinical studies on surgical treatment of rectal cancer; * 4\. The patient has a history of malignant tumor, or a combination of other malignant tumors; * 5\. Patients have been treated with definitive treatment: radiotherapy, chemotherapy or immunotherapy; * 6\. Patients had received otherper abdominal operations (except for laparoscopic cholecystectomy); * 7\. ASA \>3; * 8\. Laparoscopic surgical contraindications: such as severe heart lung disease; abdominal wall hernia; diaphragmatic hernia; coagulation disorder; portal hypertension; pregnancy, etc.; * 9\. Those who has been confirmed to be unable to do a radical resection (T4 stage) for local advanced tumor; * 10\. Those who have urination sexual dysfunction preoperatively.