Combined spinal epidural anesthesia (CSEA) is applied to lower limb orthopaedic surgery in the elderly. This study aims to explore the effect of CSEA in orthopaedic surgery of elderly patients. A total of 40 elderly patients with femoral fracture needing hip replacement or femoral head replacement in our hospital from June 2021 to June 2022 were selected as the research objects. The subjects were divided into observation group (n = 20) and control group (n = 20) by random number table method. The control group was given epidural anesthesia, while the observation group was given CSEA. Hemodynamic indexes heart rate (HR) and mean arterial pressure (MAP), visual analogue scale (VAS) pain score changes, anesthetic effects, and post-operative complications were compared between the two groups. After operation, the observation group had lower HR and MAP values than the control group. The dosage of local anesthetics in the observation group was significantly less than that in the control group. The onset time and improvement time of sensory block in the observation group were significantly faster than those in the control group. The observation group had a lower VAS score than the control group. There was no significant difference in Bromage score or incidence of complications between the two groups. The use of low-dose local anesthetics has good anesthetic effect. When the anesthesia level is controlled below T8, it has the advantages of little impact on the circulatory and respiratory system, rapid postoperative recovery, and less complications. In addition, it has the disadvantage of no headache after traditional spinal anesthesia, is not limited by time and can be used for postoperative analgesia, which is more suitable for the anesthesia of lower limb orthopaedic surgery in the elderly.