Abstract: [Objective] The objective of this study is to investigate the diagnostic value of neutrophil extracellular traps (NETs) content in peripheral blood for postoperative pneumonia in elderly patients with hip fracture. [Methods] A total of 57 elderly patients with hip fracture undergoing surgical treatment in our hospital from January 2019 to February 2022 were prospectively selected and divided into non-pneumonia group (n=38) and pneumonia group (n=19) according to the incidence of postoperative pulmonary infection. The level of NETs in peripheral blood of 2 groups were compared. Logistic regression analysis was used to investigate the risk factors of postoperative pneumonia. Receiver operating characteristic (ROC) curve to evaluate the predictive value of NETs content in peripheral blood for postoperative pneumonia. Subgroup analysis was performed according to the optimal cut-off value of the ROC curve to analyze the difference in the incidence of pneumonia among patients. [Results] Compared to control group, the patients with postoperative pneumonia had a higher level of NETs (3.59±0.74 vs. 6.48±1.96; P＜0.05). Correlation analysis showed that the level of NETs in peripheral blood were positively correlated with postoperative pulmonary infection (r=0.641, P＜0.05). Logistic regression analysis showed that the level of NETs was a risk factors for postoperative pneumonia [OR=7.289, 95%CI:(1.980~26.836); P＜0.05]. ROC curve showed that the area under curve (AUC) of NETs content in peripheral blood predicting postoperative pulmonary infection was 0.892. Base on NETs≥4.20 as a predictor of best cut-off value of predicting the occurrence of postoperative pneumonia in patients with a sensitivity of 84.21% and specificity of 76.32%. Subgroup analysis showed that the incidence of postoperative pneumonia in patients with peripheral blood NETs content ≥4.20 was significantly higher than that in patients with peripheral blood NETs content < 4.20 (64.00% vs. 9.38%, P< 0.01). [Conclusion] The level of NETs in peripheral blood of elderly patients with hip fracture increased after operation.