As primary drivers of underlying microbial changes, soil metals have been extensively studied in agroecosystems. However, while their contributions to forest soil microbial processes are crucial for maintaining tree biodiversity, they remain poorly understood. Based on the analysis of 1287 soil samples collected from a 20 ha forest plot, we show that seven metal elements (Al, Ca, Cu, Fe, Mg, Mn, and Zn) shape microbial community structure and function by initially altering influential microbial taxa. Microbial α-diversity and community structure responded differently to these elements at low vs. high C:N ratios, pH, and water content. Moreover, these elements also affected microbial functional guilds (e.g., phosphorus and sulfur metabolism, ectomycorrhizae, plant pathogens, and wood saprotrophs) via sensitive microbial taxa. This study advances our capacity to predict belowground microbial processes by revealing the fundamental importance of metals in forest soils, with important implications for better conserving forest biodiversity under global climate change.