Objective To explore the efficacy and complication of total hip arthroplasty in the treatment of ankylosing spondylitis hip joint ankylosis,and analyze its prognosis.Methods Eighty-two patients with ankylosing spondylitis hip joint ankylosis were divided into observation group and control group by random digits table method,the 42 patients in observation group were given total hip arthroplasty after the diagnosis of early,the 40 patients in control group were given delayed total hip arthroplasty.In the 2 groups,the recovery of hip joint function were observed,postoperative complication were recorded,and the 5-year survival rate situation were followed up.Results The activity of hip joint,degree of hip joint flexion and Harris score after operation in the 2 groups were significantly better than those before operation,there were statistical differences (P ＜ 0.05),the indexes after operation in observation group were significantly better than those in control group [activity of hip joint:175.25° ± 15.52° vs.122.95° ± 16.26° ; degree of hip joint flexion:85.65° ± 5.33° vs.70.78° ± 4.97° ;Harris score:(86.08 ± 5.41) scores vs.(73.92 ± 6.62)scores],there were statistical differences (P ＜ 0.05).Infection occurred in 1 case,dislocation in 0 case,prosthesis loosening in 2 cases in observation group,the rate of complication was 7.14％(3/42).Infection occurred in 5 cases,dislocation in 2 cases,prosthesis loosening in 4 cases in control group,the rate of complication was 27.50％ (11/40).The rate of complication in observation group was significantly lower than that in control group,there was statistical difference (x2 =8.34,P＜ 0.01).The 1,3-year survival rate in observation group was higher than that in control group,but there was no statistical differences (P ＞ 0.05).The 5-year survival rate in observation group was significantly higher than that in control group [90.48％(38/42) vs.70.00％ (28/40)],there was statistical difference (x2 =7.57,P ＜ 0.01).Conclusion Early total hip arthroplasty has significantly clinical effects in the treatment of patients with ankylosing spondylitis hip joint ankylosis,and its early operation curative effect is better than that of delayed operation.