Objective To explore the efficay of combined spinal-epidural anesthesia with light and heavy bupivacaine in the elderly undergoing hip replacement. Methods A total of 112 elderly patients undergoing hip replacement in our hospital from February 2016 to February 2018 were subjected in this study. According to the types of anesthesia, they were divided into observation group (3ml 0.25% light specific gravity bupivacaine combined spinal-epidural anesthesia) and control group (3 ml 0.50% heavy specific gravity bupivacaine combined spinal-epidural anesthesia), with 56 cases in each group. The anesthetic effect, heart rate (HR), mean arterial pressure (MAP), and arterial oxygen saturation (SpO₂) before and 5,0, 15,0 and 60min after anesthesia (T1-T5), and severity of lower extremity motor block (assessed by modified Bromage scale) and adverse events were compared between the 2 groups. SPSS statistics 17.0 was used to analyze the data. Results Compared with the control group, the observation group had significantly longer duration of anesthesia maintenance [(123.3±10.5) vs (110.2±10.3)s, P=0.031], while shorter onset times of sensory block [(35.6±7.4) vs (45.7±7.9)s, P=0.008] and of motor block [(235.7±34.7) vs (270.7±39.7)s, P=0.041]. There was no significant difference in HR between the 2 groups at T0-T3 (P>0.05), but HR was significantly lower in the observation group than the control group at T4-T5 (P<0.05). No significant difference was seen in [JP+1]MAP between the 2 groups at T0-T5 (P>0.05).SpO₂ in the observation group was significantly higher than that in the control group at T1-T4 time points (P<0.05). HR, MAP and SpO₂ levels in the observation group were slightly different at different time points from T0 to T5, but without significant differences (P>0.05). Compared with T0, HR of T1-T5 and MAP of T2-T5 in the control group changed significantly (P>0.05). Compared with pre-operation, the proportion of Bromage grade 2 in the observation group (P=0.013) and the control group (P=0.015) was increased significantly, while the proportion of grade 3 (P=0.038; P=0.021) was decreased significantly. At the same time, the proportion of grade 1 (P=0.021) and grade 2 (P=0.039) in the observation group was significantly higher than that in the control group. There was a significant difference in the incidence of adverse reactions between the 2 groups [8.9%(5/56) vs 37.5%(21/56); P=0.000]. Conclusion Light specific gravity bupivacaine combined with spinal epidural anesthesia is superior to heavy specific gravity bupivacaine in elderly patients undergoing hip replacement, because of its reducing intraoperative hemodynamic fluctuations and the occurrence of adverse events, and of high reliability and safety.