Objective <p>Intraoperative hypothermia has significant effects on physiological functions such as anti-infection and coagulation, but its association with specific postoperative pulmonary complications (PPCs) still remains unclear. The objective of this study is to explore the association between intraoperative hypothermia and PPCs.</p> Methods <p>This study retrospectively analyzed 311 consecutive elderly patients who received off-pump coronary artery bypass grafting (OPCABG) at Xuanwu Hospital between January 2019 and April 2024. Baseline characteristics, intraoperative data, anesthesia records, perioperative laboratory parameters and post-surgery outcomes were gathered. Univariate analysis and multivariate logistic regression were performed to assess the association between intraoperative hypothermia and the occurrence of PPCs.</p> Results <p>Among the 311 patients, 134 experienced intraoperative hypothermia, defined as the intraoperative core temperature &lt; 36.0&#xa0;°C lasting for more than 5&#xa0;min, with the incidence rate of 43.1%. Compared with the non-hypothermia group, the hypothermia group showed significantly higher incidence of postoperative pleural effusion and respiratory infection. Further multivariate logistic regression analysis confirmed that intraoperative hypothermia was an independent risk factor for postoperative pleural effusion (OR: 2.725, 95% CI: 1.656 ~ 4.484, <i>P</i> &lt; 0.001) and respiratory infection (OR: 2.342, 95% CI: 1.336 ~ 4.105, <i>P</i> = 0.003).</p> Conclusion <p>Intraoperative hypothermia is significantly associated with the increased risk of postoperative pleural effusion and respiratory infection in elderly patients undergoing OPCABG. This finding highlights the important role of strict intraoperative temperature management in reducing the incidence of these two PPCs. Multicenter prospective studies are warranted to validate the causal relationship and explore optimal temperature management strategies.</p>