Objective To investigate the intraoperative muscle-relaxant effect and safety of Cis-atracurium on the patients with impaired renal function. Methods 20 patients with impaired renal function undergoing emergency laparotomy were the observation group, 20 patients with normal renal function undergoing emergency laparotomy were the control group. All patients were anesthetized and maintained in the same method. Neuromuscular blocking effects were monitored using the Organon accelograph. The onset time(T1 up to a maximum block time), no reaction time(T1 of the greatest block to T1 recovery), T1 25% recovery time, T1 75% recovery time and recovery index(T1 recovery from 25% to 75% of the time) were recorded. Results There were not significant differences in sex, height, weight and operative time between two groups(P＞0.05). The renal function indicators[blood urea nitrogen (15.4±5.6) mmol/L, serum creatinine (320±45) μmol/L] in the observation group were higher than those [blood urea nitrogen (4.4±2.6) mmol/L, serum creatinine (132±25) μmol/L] in the control group(P<0.05). The onset time in the observation group is slightly longer than that in the control group, but the difference was not significant(P>0.05). There were no significant difference in no reaction time, T1 25% recovery time, T1 75% recovery time and recovery index between two groups(P>0.05). Conclusions Cis-atracurium could be safely used in patients with impared renal function.