〔Abstract〕 Objective To investigate the value of metagene next-generation sequencing (mNGS) in the detection of pathogens in patients with pulmonary infection. Methods A retrospective analysis was performed on clinical data from 434 patients with pulmonary infections admitted over the past four years. Based on the presence of underlying comorbidities, patients were divided into underlying disease group ( n=262) and non-underlying disease group ( n=172). Pathogen detection was conducted using both mNGS and conventional tests. Clinical and laboratory parameters, radiographic findings, and pathogen detection results were systematically analyzed. The diagnostic performance of the two methods in identifying causative pathogens of pulmonary infections was compared. Results The positive rate of mNGS in 434 patients was higher than that of conventional tests, and the difference was statistically significant ( P<0.05). The efficacy of mNGS in detecting bacteria and viruses was significantly higher than that of conventional tests, and the difference was statistically significant ( P<0.05). Although the fungal detection rate of mNGS was higher than that of conventional tests, the difference was not statistically significant. Among them, the detection rates of Mycobacterium tuberculosis, Mycoplasma pneumoniae, Haemophilus influenzae, Streptococcus pneumoniae, Streptococcus constellation, Staphylococcus aureusand Aspergillus fumigatus were significantly higher than those of conventional tests, and the difference was statistically significant ( P<0.05). Subgroup analysis showed that the proportion of males, hospital stay, smoking prevalence and average age in the underlying disease group were higher than those in the non-underlying disease group, and the difference was statistically significant ( P<0.05), while there were no significant differences in antibiotic use and endotracheal intubation rate between the two groups. The most common pathogens detected by mNGS in the underlying disease group were Mycobacterium tuberculosis, Haemophilus influenzae, Streptococcus pneumoniae, Pseudomonas aeruginosa, human herpesvirus type 4and Aspergillus fumigatus, while the most common pathogens in the non-underlying disease group were Mycobacterium tuberculosis, Haemophilus influenzae, Streptococcus pneumoniae, Mycoplasma pneumoniaeand Klebsiella pneumoniae.The positive rate of mNGS in the two groups was significantly higher than that of conventional tests, and the difference was statistically significant ( P<0.05), while the difference in the positive rate of mNGS between the two groups was not statistically significant. Conclusion mNGS has significant advantages over conventional tests of pathogen in lung infection, and is less affected by underlying diseases, which can provide an etiological basis for lung infection.