Objective:To investigate the effect of propofol closed-loop target-controlled infusion system in controlling the bispectral index (BIS) at different levels during artificial hip replacement in the elderly under general anesthesia combined with nerve block on postoperative delirium, postoperative pain and intraoperative circulation control.Methods:From October 2017 to May 2019, 95 elderly patients with elective unilateral artificial hip replacement were selected from Xiangya Hospital of Central South University. They were randomly divided into light anesthesia group (48 cases) and deep anesthesia group (47 cases). Under general anesthesia combined with nerve block, the target BIS value of propofol closed-loop target-controlled infusion in the light anesthesia group was set to 55±5, and the target BIS value of the deep anesthesia group was 45±5. The incidence of postoperative delirium and postoperative pain visual analogue scale (VAS) score were observed. The changes of hemodynamics, intraoperative vasoactive drug use, propofol dosage and intraoperative BIS value at different time points were compared between the two groups.Results:There was no significant difference in the incidence of postoperative delirium and the VAS score of postoperative pain between the two groups ( P>0.05). The average intraoperative BIS and the ratio of intraoperative BIS>50 in the light anesthesia group were higher than those in the deep anesthesia group ( P<0.001), and the intraoperative propofol consumption was lower than the deep anesthesia group ( P<0.001); In the light anesthesia group, the arterial systolic blood pressure level after laryngeal mask implantation and skin incision during the induction period of general anesthesia was higher than that in the deep anesthesia group ( P<0.05), and the number of cases of phenylephrine use in the light anesthesia group was lower than that of the deep anesthesia group ( P<0.05). Conclusions:When using general anesthesia combined with nerve block for the elderly artificial hip replacement, the different control levels of BIS in the closed-loop target-controlled infusion of propofol have no effect on postoperative pain and postoperative delirium, but the intraoperative BIS value controlled at a lower level is related to the suppression of the patient′s hemodynamics and brings more propofol consumption.