BackgroundPostoperative pneumonia is a serious complication in elderly patients with hip fracture. It is necessary to identify the influencing factors of postoperative pneumonia in patients with hip fracture.MethodsElderly patients with hip fractures admitted to a tertiary hospital in China from January 1, 2020 to August 31, 2021 were included. The characteristics of patients with and without postoperative pneumonia were evaluated and compared. Logistic multivariate regression analyses were conducted to assess the risk factors of postoperative pneumonia.Results267 patients with hip fracture were included, the incidence of postoperative pneumonia in patients with hip fracture was 13.11%. There were significant differences in the age, diabetes mellitus, anemia, hypoalbuminemia, anesthesia method and duration of surgery between infection and no infection group, no significant differences in the gender, BMI, hypertension, hyperlipidemia, type of fracture, preoperative oxygen saturation, white blood cell count, platelet count, red blood cell count, creatinine, alanine aminotransferase, aspartate aminotransferase, estimated blood loss during surgery were detected between infection and no infection group. Logistic regression analysis showed that age≥70y (OR2.326, 95%CI1.248~3.129), diabetes mellitus (OR2.123, 95%CI1.021~3.551), anemia (OR3.199,95%CI1.943~5.024), hypoalbuminemia (OR2.377, 95%CI1.211~3.398), general anesthesia (OR1.947, 95%CI1.115~3.038), duration of surgery≥120min (OR1.621, 95%CI1.488~2.534) were the risk factors of postoperative pneumonia in elderly patients with hip fracture (all p<0.05). Escherichia Coli (33.33%), Klebsiella pneumoniae (28.57%), Staphylococcus aureus (21.43%) were the most common bacteria of pulmonary infection.ConclusionThere are many risk factors for postoperative pneumonia in elderly patients with hip fractures after surgery. In clinical practice, medical workers should take targeted interventions for those risk factors to reduce postoperative pneumonia.