Objective To explore the reliability and accuracy of the arbitrary point method for measuring the anteversion angle of acetabular prosthesis after total hip arthroplasty (THA) based on pelvic X-ray films. Methods The clinical data of 23 patients (25 hips) who underwent THA between December 2018 and September 2023 and met the selection criteria were retrospectively analyzed. Among them, there were 16 males and 7 females, with an average age of 57.6 years (range, 34-81 years); 13 hips had THA on the left side and 12 on the right side. There were 19 cases (21 hips) of osteonecrosis of the femoral head, 2 cases (2 hips) of femoral neck fractures, 1 case (1 hip) of developmental dysplasia of the hip, and 1 case (1 hip) of osteoarthritis. After THA, all patients underwent X-ray examination and CT scan. Three physicians measured the anteversion angle of acetabular prosthesis using the arbitrary point method and the CT measurement method respectively, and repeated the measurements three times. The results of the two measurement methods were compared, and the intraclass correlation coefficient (ICC) was employed to assess the reproducibility of the methods. Results The anteversion angles of acetabular prosthesis were (15.87±7.73)° measured by the arbitrary point method, and (15.31±7.89)° measured by CT measurement method. There was no significant difference between the two methods (t=1.515, P=0.143). The ICC of the measurement results by the arbitrary point method for the three physicians were 0.97 (P<0.001), 0.96 (P<0.001), and 0.96 (P<0.001), respectively; and the ICC of the measurement results by CT method were 0.93 (P<0.001), 0.93 (P<0.001), and 0.94 (P<0.001), respectively. Conclusion The arbitrary point method for measuring the anteversion angle of acetabular prosthesis after THA based on pelvic X-ray film is easy to operate, accurate, and has high reproducibility.