Objective Metagenomic next-generation sequencing (mNGS) has the potential to overcome the shortcomings of traditional culture methods. This study aimed to assess the diagnostic value of mNGS in patients with lower respiratory tract infections (LRTIs). Methods This retrospective observational study sequentially enrolled 47 patients with LRTIs admitted to Shenzhen Hospital of Southern Medical University between February 2019 and November 2020. Pathogens in bronchoalveolar lavage fluid (BALF) samples were investigated to compare diagnoses by mNGS with culture methods. Results Compared with culture methods, mNGS had a diagnostic sensitivity of 80% and a specificity of 35.13% with an agreement rate of 44.68% between these two methods. mNGS significantly increased the pathogen detection rate. Conclusions mNGS may show some advantages in identifying a wide range of LRTI pathogens, improving the sensitivity for viruses and atypical pathogens. The clinical application of NGS technology is worth looking forward to.