Treeline shifts are likely to have a profound impact on the distribution of biodiversity and the maintenance of ecosystem functioning. Understanding the community structure and functioning of soil microorganisms around the treeline is crucial for predicting the response of ecosystems to global climate change. In this study, we investigated the soil bacterial communities and their function in a Quercus liaotungensis forest and the meadow above the treeline at Mount Dongling, using 16S rRNA gene sequencing and PICRUSt analysis. The results showed that soil bacterial species richness did not significantly change at the treeline, and there was no obvious trend along the elevation gradient. However, the bacterial community structure and the predicted functional profiles changed at the treeline. Within the 39 predicted functional categories at KEGG pathway hierarchy level 2, 11 categories showed apparent differences between forest and meadow. Relative abundance of gene families related to biosynthesis of other secondary metabolites, transcription, glycan biosynthesis and metabolism, enzyme families, signaling molecules and interaction, environmental adaptation, growth, and death tended to be higher in the forest, whereas the abundance of gene families related to metabolism of cofactors and vitamins, membrane transport, and the endocrine system were significantly higher in the meadow. In future studies of microbial ecology, more attention should be paid to community composition and functioning instead of species diversity.