Objective To systematically evaluate the influencing factors for pulmonary infection after cardiac surgery. Methods Literatures were retrieved from PubMed, Embase, Web of Science, the Cochrane Library, CBM, Wanfang, CNKI and VIP databases. The retrieval time was from the establishment of databases to November 22, 2022. Meta-analysis was performed with RevMan 5.4 and Stata 15.0 softwares. Results A total of 20 literatures were included in the analysis. Meta-analysis showed that age (≥ 65 years), mechanical ventilation time (≥ 5 days), smoking, acute renal damage, perioperative blood transfusion, operation time (≥ 240 minutes), secondary thoracotomy, and oxygenation index (PaO₂/FiO₂ ≤ 300 mmHg) were risk factors for postoperative pulmonary infection. Conclusion The existing evidence shows that all of the above 8 factors are risk factors for pulmonary infection after cardiac surgery, which can provide a theoretical basis for health care workers to prevent and treat infection.