ObjectiveTo systematically evaluate the risk factors for pulmonary infection after cardiac surgery. MethodsA computer search was performed to collect researches on risk factors for pulmonary infection in patients after cardiac surgery from the databases, including CNKI, Wanfang, VIP, CBM, PubMed, The Cochrane Library, EBSCO, CINAHL, Web of Science, EMbase from the inception to August 2023. Two researchers independently extracted data and assessed the literature according to the inclusion and exclusion criteria, and the quality of the literature was evaluated using the Newcastle-Ottawa Scale (NOS). The meta-analysis was performed using RevMan 5.4 software. ResultsA total of 23 studies covering 24348 patients were selected, including 21 case-control studies and 2 cohort studies. The NOS scores were≥6 points. The results of meta-analysis showed that age (OR=2.16, 95%CI 1.80 to 2.59, P<0.001), smoking history (OR=1.91, 95%CI 1.67 to 2.18, P<0.001), pulmonary disease (OR=1.61, 95%CI 1.40 to 1.85, P<0.001), diabetes mellitus (OR=1.62, 95%CI 1.26 to 2.08, P<0.001), operation time (OR=2.54, 95%CI 1.86 to 3.46, P<0.001), cardiopulmonary bypass (CPB) (OR=3.78, 95%CI 2.11 to 6.77, P<0.001), CPB time (OR=2.30, 95%CI 1.94 to 2.71, P<0.001), blood transfusion (OR=2.55, 95%CI 2.04 to 3.20, P<0.001), postoperative mechanical ventilation time (OR=2.78, 95%CI 2.34 to 3.30, P<0.001), tracheal intubation time (OR=3.93, 95%CI 2.45 to 6.31, P<0.001) and repeated tracheal intubation (OR=8.74, 95%CI 4.17 to 18.30, P<0.001) were independent risk factors for pulmonary infection in patients after cardiac surgery. ConclusionAge, smoking history, pulmonary disease, diabetes mellitus, operation time, CPB, CPB time, blood transfusion, postoperative mechanical ventilation time, tracheal intubation time, and repeated tracheal intubation are risk factors for pulmonary infection in patients after cardiac surgery. It can be used as a reference to strengthen perioperative evaluation and nursing of high-risk patients and reduce the incidence of pulmonary infection.