Objective To investigate the effect and safety of total hip arthroplasty in the treatment of old femoral neck fracture in the elderly. Methods Thirty-six elderly patients with old femoral neck fracture were treated with total hip arthroplasty. The average age of patients was 81.2 years, and the mean disease duration of bone fracture was 9.4 months. The perioperative complications were retrospectively analysed, and the function of hip joint was evaluated after operation. Results The walking ability was recovered in all patients. The Harris hip score increased from 35.6±8.4 before operation to 86.7±6.2 six months after operation, with the overall excellent rate of 91.7% (33/36). Postoperative complications included lung infection, urinary tract infection, transient disturbance of consciousness, water electrolyte disorder and low protein edema. There was no perioperative death. Conclusion Total hip arthroplasty is an effective treatment for old femoral neck fracture in the elderly. Perfect preoperative and perioperative management are important for favorable outcomes.