〔Abstract〕 Objective To analyze the application value of metagenomic next-generation sequencing(mNGS) in the detection of pathogenic bacteria in pulmonary infection, and to provide a theoretical basis for clinical diagnosis. Methods A retrospective study was conducted on 161 patients with suspected pulmonary infection, and samples of bronchoalveolar lavage fluid, sputum and lung tissue were collected specimens, pleural effusion and blood were simultaneously subjected to routine culture, respiratory pathogen nucleic acid detection and pathogenic microorganism mNGS detection. The sensitivity, specificity, positive predictive value, and negative predictive value of the three detection methods were calculated respectively to evaluate the clinical application value of mNGS. Results Among 161 patients with suspected pulmonary infection, 113 cases were finally confirmed as pulmonary infection. Among the 161 patients enrolled, the sensitivity and negative predictive value of mNGS were improved compared with routine culture and nucleic acid detection of respiratory pathogens, and the difference was statistically significant(P<0.001). Although the specificity of mNGS was higher than that of respiratory pathogen nucleic acid detection, the difference was not statistically significant. The positive predictive value of mNGS was the highest, and was higher than that of respiratory pathogen nucleic acid detection, but had no statistical significance compared with conventional culture. Conclusion The sensitivity of mNGS in the diagnosis of pathogenic microorganisms in pulmonary infection is higher than that of conventional culture and nucleic acid detection of respiratory pathogens, which reduces the false negative rate of diagnosis and has a better comprehensive evaluation; conventional culture detection has low sensitivity, but high specificity; respiratory pathogen nucleic acid detection compared with conventional culture, the sensitivity is improved, but the specificity decreased.