ObjectiveTo systematically evaluate the risk factors for postoperative pulmonary infection in patients with esophageal cancer. MethodsCNKI, Wangfang Data, VIP, CBM, PubMed, EMbase, The Cochrane Library were searched from inception to January 2021 to collect case-control studies, cohort studies and cross-sectional studies about risk factors for postoperative pulmonary infection in patients with esophageal cancer. Two researchers independently conducted literature screening, data extraction and quality assessment. RevMan 5.3 software and Stata 15.0 software were used for meta-analysis. ResultsA total of 20 articles were included, covering 5 409 patients of esophageal cancer. The quality score of included studies was 6-8 points. Meta-analysis results showed that age (MD=1.99, 95%CI 0.10 to 3.88, P=0.04), age≥60 years (OR=2.68, 95%CI 1.46 to 4.91, P=0.001), smoking history (OR=2.41, 95%CI 1.77 to 3.28, P<0.001), diabetes (OR=2.30, 95%CI 1.90 to 2.77, P<0.001), chronic obstructive pulmonary disease (OR=3.69, 95%CI 2.09 to 6.52, P<0.001), pulmonary disease (OR=2.22, 95%CI 1.16 to 4.26, P=0.02), thoracotomy (OR=1.77, 95%CI 1.32 to 2.37, P<0.001), operation time (MD=14.08, 95%CI 9.64 to 18.52, P<0.001), operation time>4 h (OR=3.09, 95%CI 1.46 to 6.55, P=0.003), single lung ventilation (OR=3.46, 95%CI 1.61 to 7.44, P=0.001), recurrent laryngeal nerve injury (OR=5.66, 95%CI 1.63 to 19.71, P=0.006), and no use of patient-controlled epidural analgesia (PCEA) (OR=2.81, 95%CI 1.71 to 4.61, P<0.001) were risk factors for postoperative pulmonary infection in patients with esophageal cancer. ConclusionThe existing evidence shows that age, age≥60 years, smoking history, diabetes, chronic obstructive pulmonary disease, pulmonary disease, thoracotomy, operation time, operation time>4 h, single lung ventilation, recurrent laryngeal nerve injury, and no use of PCEA are risk factors for postoperative pulmonary infection in patients with esophageal cancer. Due to the limitation of the quantity and quality of included literature, the conclusion of this study still needs to be confirmed by more high-quality studies.