[Objective] We explore the impact of primary forest conversion on soil microbial community structure and predicting soil microbial functions, and provide theoretical reference for soil health preservation. [Methods] The subtropical typical primary evergreen broad-leaved forest and the adjacently converted conifer plantation, orchards, sloping tillage, and rice paddy were chosen in northwest Hunan province. We assessed the response of bacterial and fungal genomic diversity, community structure, and predicted functions to the primary forest conversion. [Results] Comparing to the primary forest, the bacterial diversity was decreased by 29%-34% in the cultivated lands, whereas fungal diversity was decreased by 42%-49% in the orchards. The response direction and magnitude of soil bacterial and fungal predicted function depended on the specific soil function and converted land-use type. Comparing to the primary forest, the relative abundance of global and overview maps, carbohydrate metabolism, and metabolism of cofactors and vitamins were 9%-25% higher in orchards and croplands, whereas the relative abundance of membrane transport, signal transduction, cellular community?prokaryotes were 11%-27% lower in orchard and croplands. The relative abundance of endophyte-litter saprotroph?soil saprotroph in sloping tillage were 32%-42% lower than those in the primary forest; however, the animal pathogen and plant pathogen were 10%-397% higher than those in the primary forest. No significant differences of >50% of the relative abundance of predicted microbial functions were found between the primary forest and plantations. The labile C and total N contents decreased by 25%-70% following the primary forest conversion, resulting in a 10%-86% reduction in the relative abundances of variibacter and bradyrhizobium, which was the main pathway regulating the predictive functions of soil bacteria. In addition, the predicted bacterial function is mainly regulated by soil moisture and labile organic C content, whereas the predicted fungal function is mainly regulated by soil pH, quantity of labile organic C, and nutrient availability. [Conclusion] This study suggests that the conversion of primary evergreen broad-leaved forest to Cunninghamia lanceolata plantation is relatively conducive to the maintenance of soil health and functional potential, whereas the conversion to sloping tillage can increase the risk of soil-borne diseases on crops. Our findings provide a theoretical basis for prediction regional soil health evolution and rational land planning.