Objective To discuss the feasibility and safety of total mesorectal excision under laparoscopy by ultrasonic scalpel for rectal carcinoma. Methods The data of 83 patients with rectal carcinoma who received gastrointestinal surgery under laparoscopy in our hospital from March 2011 to September 2013 were analyzed. According to the method of total mesorectal excision,they were divided into ultrasound knife group of 44 cases and a high-frequency electric knife group of 39 cases. The differences of the intraoperative and postoperative related index between two groups were compared and the postoperative complications were analyzed. Results All gastrointestinal operations under laparoscopy were completed successfully. The operation time(221. 6 ± 48. 7) min and the peri-operative bleeding (64. 2 ± 39. 5) mL of ultra-sound knife group were significantly lower than the operation time(284. 3 ± 52. 4) min and the peri-operative bleeding (98. 7 ± 49. 3) mL of high frequency electric knife group (P<0. 05). Intraoperative dissected lymph node number (7. 8 ± 2. 7) of ultrasound knife group was sig-nificantly higher than that of the high frequency electric knife group (5. 2 ± 2. 2) (P<0. 05). The difference of anal exhaust time and post-operative hospital stay between two groups was not statistically significant (P>0. 05). The volume of harmful gas included CO and acryloni-trileis at the 15min,30min,45min during the operation of ultrasound knife group were significantly lower than that of high frequency electric knife group (P<0. 05). There was no statistically significant difference in complication rate between the two groups (P>0. 05). Conclu-sion Treatment of laparoscopic surgery for rectal cancer by ultrasonic scalpel in total mesorectal excision has the advantages of less operation time,intraoperative blood loss and less harmful gases,which is effective and safe.