Abstract: Objective To compare the clinical outcomes of robot-assisted anterior resection of rectum between 3-arm and 2-arm system. Methods Clinical data about 110 cases with rectal cancer who received robot-assisted anterior resection of rectum from Sept. 2014 to Oct. 2016 were reviewed. Fifty patients who received robot-assisted anterior resection of rectum with 3-arm system were chosen as the observation group and 60 patients who received robot-assisted anterior resection with 2-arm system were the control group. Results The baseline data were well matched in two groups. Compared to the control group, the surgery using 3 robot arms had the advantage of shorter operating time (136.4±4.5) min vs (152.8±3.9) min, P=0.005, less blood loss (45.9±10.9) ml vs (59.3±16.3) ml, P=0.036, shorter period of indwelling gastric tube (43.9±0.6) h vs (48.6±0.8) h, P=0.001, shorter time to ambulation (15.9±0.5) h vs (18.9±0.7) h, P=0.000, shorter hospital stay (8.12±1.66) d vs (10.67±1.72) d, P=0.036, but the cost was higher than the control group (10.4±0.3) ten thousand yuan vs (8.1±0.5) ten thousan yuan, P=0.002. In addition, the period of indwelling urinary catheter and postoperative complications were not significant different between observation group and control group. Conclusion The robot-assisted anterior resection with 3 robotic arms is feasible and safe for rectal cancer patients comparing with using 2 robot arms. Quick recovery and satisfying short-term clinical outcomes are achieved, but the cost is high.