Abstract: Objective To compare the efficacy of propofol closed-loop target-controlled infusion and open-loop manual regulated infusion in colorectal cancer surgery. Methods A total of 110 patients with colorectal cancer undergoing surgery were divided into study group(55 cases) and control group(55 cases) according to random number table method. The patients in the study group received intraoperative propofol infusion with closed-loop target-controlled infusion system guided by BIS, while the patients in the control group received intraoperative propofol infusion with manual adjustment. HR, MAP and SPO₂ were monitored on T1(before induction of anesthesia), T2(at intubation), T3(at skin incision), T4(after operation) and T5(at extubation) time points. The operation time, duration of anesthesia, dosage of propofol during anesthesia, recovery time of spontaneous breathing, time to recovery and extubation were recorded. The adverse reactions to anesthesia were observed. The recovery of cognitive function after anesthesia resuscitation were evaluated. Results The value of MAP at T2-T4 and HR at T2 in the study group was significantly higher than those in the control group( all P<0.01), while HR at T3 and T4 in the study group were significantly lower than that in the study group(all P<0.01). The dosage of propofol during anesthesia in the study group was(647.51±24.62)mg, which was significantly lower than that in the control group [(783.18±31.76)mg], and the recovery time of spontaneous breathing, recovery time and time to extubation were significantly shorter than those in the control group(all P<0.001). The MMSE score of the study group(26.69±1.32) was significantly higher than that of the control group(24.95±1.46) on the 1 st day after operation(t=-3.802, P<0.001). The overall incidence of adverse reactions to anesthesia in the study group(9.09%) was significantly lower than that in the control group(25.45%, χ²=5.153, P=0.023). Conclusion The closed-loop target-controlled infusion system of propofol under BIS guidance is more conducive to maintaining stability of the hemodynamic and depth of anesthesia, reducing the dosage of anesthetics, shortening the time of anesthesia resuscitation, reducing adverse reactions of anesthesia, promoting the recovery of cognitive function and improving the safety of anesthesia in patients undergoing colorectal cancer surgery.