Abstract: Objective To explore the influence of iliac fascia combined with lumbosacral plexus blocks on perioperative hemodynamics and cognitive function in elderly patients undergoing hip replacement. Methods A total of 100 elderly patients who underwent hip replacement were divided into two groups according to the random number table method, with 50 cases in each group. Nerve block group was given ultrasound-guided iliac fascia combined with lumbosacral plexus nerve block, and control group was given general anesthesia alone. The changes of perioperative hemodynamic indicators, surgery time, anaesthetic dosage, intraoperative bleeding volume, 24 h total bleeding volume, postoperative analgesia effects and cognitive function were compared between the two groups. Results At time points from T₁ to T₄, there were no significant differences in hemodynamic indexes compared with T₀ in the nerve block group(P>0.05), while systolic blood pressure(SBP), diastolic blood pressure(DBP)and mean arterial pressure(MAP)in the same time points in the control group were significantly - lower, while heart rate(HR)was significantly higher than those at time point of T₀(P<0.05). The above indicators at time points from T₁ to T₄ showed significant differences in the two groups(P<0.05). There were no significant differences in the surgery time, intraoperative blood loss, and total blood loss within 24 hours in the nerve block group compared with the control group(P>0.05). The dosage of sufentanil and intravenous controlled analgesia(PCIA)dosage within 48 hours after surgery in the nerve block group was significantly less than those in the control group, and the postoperative first bed-off time was significantly shorter than that in the control group(P<0.05). Visual Analogue Scale(VAS)at 1 hour and 6 hours after surgery in the nerve block group were significantly lower than that in the control group(P<0.05). There were no significant differences in VAS scores between the two groups at 12, 24 and 48 hours after surgery(P>0.05). At the 1^st day after the surgery, Mini-Mental State Examination(MMSE)scores in both groups were significantly lower than that before surgery(P<0.05), while there was no significant difference in MMSE score at the 3^rd day after the surgery between the nerve block group and the control group(P>0.05). The MMSE score and incidence of cognitive dysfunction(POCD)at the 1^st day and the 3^rd day in the nerve block group were significantly lower than those in the control group(P<0.05). Conclusion Iliac fascia combined with lumbosacral plexus block for elderly patients undergoing hip replacement is better than general anesthesia, which can not only strengthen anesthesia efficacy, maintain intraoperative hemodynamic stability, but also reduce the dosage of anesthetic drugs and the incidence of postoperative POCD.