[Objective] To observe the changes of D- dimer in AIDS patients after total hip arthroplasty.[Methods] The clinical data of 60 AIDS patients who underwent total hip arthroplasty in our hospital from January 2015 to September 2020 were retrospectively analyzed, and the patients were divided into infected group and non-infected group according to the occurrence of surgical site infection.D-dimer, ESR and CRP values of the two groups were recorded preoperatively and 1, 3 and 7 days after surgery, respectively. Pearson correlation analysis of D-dimer, ESR and CRP and receiver operating characteristic curve ROC analysis were performed.[Results] There were 11 cases in the infected group and 49 cases in the non-infected group.There were no significant differences in D-dimer, CRP and ESR between the two groups before surgery (P>;0.05);On postoperative day 1, the D-dimer of the infected group was significantly higher than that of the uninfected group (P<0.05);3 days after surgery, there was no significant difference in D-dimer between the two groups (P>0.05);On postoperative day 7, the D-dimer of the infected group was significantly higher than that of the uninfected group (P<0.05).Pearson correlation analysis showed that D-dimer was positively correlated with ESR and CRP levels in patients with AIDS before and after 3 days (P<0.05), there was a negative correlation between 1d and 7d postoperatively (P<0.05).ROC analysis showed that the area under cure (AUC) was 0.929, the accuracy was 87.54%, the specificity was 86.76%, the positive prediction rate was 79.42%, and the negative prediction rate was 94.58%.[Conclusion] In the early stage of surgical site infection after total hip arthroplasty in AIDS patients, D-dimer significantly increased, which can be used as an early warning index of surgical site infection after total hip arthroplasty in AIDS patients.