Purpose <p>To clarify the relationship between microbial community structure and function and soil C sequestration and mineralization.</p> Methods <p>This study investigates the dynamics of soil C sequestration and mineralization, along with bacterial community structure and functional gene abundance related to C cycling, in <i>Pinus tabuliformis Carr</i> forests of varying ages (3, 16, 20, and 28&#xa0;years) on reclaimed mine soils (RMSs) in the Loess Plateau, China.</p> Results <p>Restoration age significantly influences soil C stocks, with 28-year-old soils exhibiting the highest soil C stock and the lowest bulk density (BD), while 3-year-old soils had the lowest C stocks. Soil CO₂ flux rates were highest in the 28- and 20-year-old soils. Cumulative C mineralization increased with restoration age, with the 28-year-old soils exhibiting the highest cumulative release. Bacterial community composition shifted significantly over time, with younger soils dominated by oligotrophic bacteria and older soils by copiotrophic bacteria. The abundance of most functional genes related to C degradation and C sequestration increased with ages. Significant positive correlations were observed between bacterial richness and soil C, as well as between total C sequestration gene abundance and soil C. Bacterial richness and total C sequestration gene abundance were both positively correlated with MBC, while C mineralization showed positive correlations with genes related to degradation of starch, hemicellulose, cellulose, and lignin.</p> Conclusions <p>This study highlights the critical role of bacterial communities and functional genes in regulating soil C sequestration and mineralization during forest restoration, offering insights into the mechanisms driving long-term soil C cycling.</p>