Objective. To compare the effect of ropivacaine in different concentrations under ultrasound guidance on lumbar muscle nerve blocking in elderly patients undergoing hip replacement surgery. Methods. 60 elderly patients underwent hip replacement in our hospital over a period of April to December of 2019 were equally randomized into control and observation groups, with 30 each. Patients in the control group and observation group received 0.5% and 0.25% ropivacaine to block psoas muscle nerve, respectively. The anesthetic effect of ropivacaine at different concentrations was evaluated by time of sensory block onset and recovery and time of motor block onset and regression, blood pressure, heart rate, visual analogy scale, and postoperative nerve blocking degree. Results. The onset time of sensory and motor block in the observation group was dramatically higher than that in the control group ( P < 0.05 ), while the recovery time of sensory and motor was significantly shorter than that of the control group ( P < 0.05 ). The heart rate in the observation group was notably lower than that in the control group, while the average blood pressure was remarkably higher ( P < 0.05 ). After surgery, the degree of nerve block in the observation group was much lower compared with the control group ( P < 0.05 ), while no marked difference in the visual analogue scale in the control group before and after surgical intervention was observed ( P > 0.05 ). Conclusion. The 0.25% ropivacaine method has distinctive advantages over 0.50% ropivacaine psoas nerve anesthesia in hip replacement surgery in elderly patients.