Objective: To study the serum inflammatory indexes, distribution of pathogenic bacteria and risk factors of patients with pulmonary infection after radical gastrectomy for gastric cancer, and to provide clinical guidance. Methods: Patients with gastric cancer who underwent radical gastrectomy in our hospital from July 2017 to July 2020 were selected as the subjects of this study, including 45 infected patients and 55 non-infected patients. Serum inflammatory indexes, pathogen distribution and risk factors of infection were compared between the two groups. Results: The serum inflammatory indexes, including WBC count, neutrophils percentage and C-reactive protein value (CRP) in the infected group were significantly higher than those in the uninfected group, with statistical significance (P<0.05). A total of 82 strains of pathogenic bacteria were isolated from 45 patients with pulmonary infection. Gram-negative bacteria accounted for most of them, with 38 strains. Then there were 24 strains of fungi and 20 strains of gram-positive bacteria, accounting for 46.34%, 29.27% and 24.39%, respectively. The risk factors of pulmonary infection include preoperative hemoglobin, catheterization time, history of diabetes mellitus, smoking history, and nutritional risk. Conclusion: Patients with gastric cancer are at risk of pulmonary infection after radical gastrectomy. Serum inflammatory indexes of infected patients are high, and Gram-negative bacteria are the main pathogen distribution. Risk factors for pulmonary infection include preoperative hemoglobin, catheter time, diabetes history, smoking history and nutritional risk, etc.