Abstract: Objective To study the clinical efficacy and strategy of cementless total hip arthroplasty（THA） in patients with ankylosing spondylitis（AS）. Methods THA was performed for 58 hip-joint lesions due to AS in 38 patients.The patients were followed up for 26.6 months（range 20-45 months）.Pain,motion and function of hip-joints were compared before and after operation.The function of hip-joint was evaluated with the Harris scoring system. Results The symptoms and function of hip-joint were significantly improved in all patients after operation.The flexion,motion and score of hip-joint before operation were increased from 22.9° to 83.3°,36.5° to 139.3°,and from 38.7 to 87.2 after operation,respectively.X-ray examination showed no looseness and dislocation of the prosthesis. Conclusion Cementless THA is a valid procedure for hip-joint lesions due to AS.