Aims <p>Litter quality significantly impacts soil organic matter decomposition through the priming effect (PE). However, how leaf litter quality affects the stoichiometric imbalance between microbial biomass and their resource and the composition of key decomposing communities linking to PE remains unclear.</p> Methods <p>This study utilized a short-term incubation with ¹³C-labeled leaf litters of <i>Phoebe sheareri</i> (low quality, high C:N and lignin:N ratios) and <i>Phyllostachys edulis</i> (high quality, low C:N and lignin:N ratios), to explore the connection between soil PE and microbial communities.</p> Results <p>We found that high-quality leaf litter resulted in a lower positive PE of native soil organic matter decomposition than low-quality litter, leading to increased litter-derived CO₂ efflux during a 60-day incubation. High-quality litter also minimized C:N imbalance between microbial biomass and resources, raising soil enzyme C:N and C:P ratios, indicating reduced microbial N and P limitations. Using DNA-based stable isotope probing and high-throughput sequencing, it was found that high-quality litter shifted soil bacterial composition toward r-strategists, with numerous Actinobacteria utilizing the ¹³C-enriched litter, while K-strategists like Proteobacteria and Acidobacteria declined. Bacterial co-occurrence networks became more interconnected with high-quality litter addition. Structural equation modeling confirmed that litter C:N influenced PE by affecting C:N imbalance and bacterial community composition.</p> Conclusions <p>Overall, this study suggests that high-quality litter induces a lower positive PE in the early stages by reducing microbial stoichiometric imbalance and promoting r-strategists, offering evidence of the microbial mechanisms behind PE.</p>