Objective To discuss the differences of the effects on open colorectal cancer operation between using ultracision harmonic scalpel (UHS) and monopolar electrosurgery. Methods Fifty-nine patients from April to December in 2007, suffering colorectal cancer in the same treatment group, underwent open radical operation, 29 by GEN300 UHS (UHS group) and 30 by monopolar electrosurgery as control group. There was no significant difference between two groups among the factors of age, gender, tumor location, Dukes staging, gross morphology and degree of histological differentiation (Pgt;0.05). Results Shorter incision was applied in UHS group than in the control group. The mean operation time of UHS group and control group were 126 and 119 min, respectively (Pgt;0.05). The mean operative blood loss was 50 (20-140) ml in UHS group and 90 (40-200) ml in control group (Pgt;0.05). There were no significant differences among factors of bowel function recovery, mean hospitalization and incidence of complications between two groups (Pgt;0.05). The mean time for postoperative drainage fluid changing from bloody to serous was 8 (2-20) h in UHS group, however, 48 (16-80) h in control group (Plt;0.05). Conclusion In open colorectal cancer operation, benefits of using UHS are shorter incision and minimally invasiveness.