Objective To investigate the infection status and influencing factors thereof in elderly patients after total hip arthroplasty.Methods Four hundred and eleven elderly patients who underwent total hip arthroplasty in our hospital from January 2015 to December 2019 were selected and divided into infection group (n = 23) and non-infection group (n = 388) according to postoperative infection status. The infection site was recorded and pathogenic bacteria were identified. The clinical data of the two groups were compared, and the indexes with differences between the groups were analyzed by multivariate Logistic regression.Results Among the 411 patients, 23 (5.60%) had nosocomial infection, of which 11 (47.83%) had respiratory tract infection, 8 (34.78%) had urinary tract infection, 2 (8.70%) had skin infection, and 2 (8.70%) had bloodstream infection. A total of 35 pathogenic bacteria were detected in 23 patients with infection, including 9 strains of Escherichia coli (25.71%), 7 strains of Staphylococcus aureus (20.00%), 7 strains of coagulase negative staphylococcus (20.00%), 6 strains of Klebsiella pneumoniae (17.14%), 4 strains of Staphylococcus epidermidis (11.43%) and 2 strains of Enterococcus faecalis (5.71%). Compared with the non-infection group, the infection group exhibited higher age, decreased levels of hemoglobin and albumin, longer durations of operation and urinary catheterization, more intraoperative blood loss and higher proportions of patients with allogeneic blood transfusion and diabetes mellitus (P < 0.05). Multivariate Logistic regression analysis showed that age > 75 years old [R = 3.328 (95% CI: 1.727, 8.414)], diabetes mellitus [R = 17.201 (95% CI: 1.201, 36.352)], operative duration > 2 hours [R = 6.424 (95% CI: 3.262, 21.197)], intraoperative blood loss > 600 ml [R = 1.015 (95% CI: 1.005, 10.025)], allogeneic blood transfusion [R = 12.026 (95% CI: 1.246, 26.045)], duration of urinary catheterization > 48 h [R = 1.545 (95% CI: 1.178, 12.028)] were risk factors for nosocomial infection after total hip arthroplasty (P < 0.05), and that hemoglobin > 100 g/L [R = 0.237 (95% CI: 0.086, 6.652)] and albumin > 28 g/L [R = 0.762 (95% CI: 0.615, 9.944)] were protective factors (P < 0.05).Conclusions Age, nutritional status, diabetes mellitus, operative duration, intraoperative blood loss, allogeneic blood transfusion and duration of catheterization are closely related to nosocomial infection after total hip arthroplasty in elderly patients.