Soil fertility is of great importance to maintain the productivity and quality of fruits, particularly in slope orchards due to their vulnerability to soil erosion and nutrient losses. However, whether and how slope orchard reclamation influences soil quality, especially soil biological characteristics during orchard development, remains unclear. In this study, changes in soil microbial biomass, community composition, and activity in a Huangguogan orchard chronosequence (1, 3, 7 and 11 years after orchard reclamation) were investigated, and their related factors were determined. The effects of orchard stand age on microbial biomass varied greatly depending on the functional group examined. Additionally, orchard stand age significantly shifted the soil microbial community composition, showing an increase in fungal dominance with increasing time since reclamation. The enzymatic activity involved in soil C cycling was sensitive and increased with orchard stand age, whereas the enzymatic activity involved in N cycling was relatively stable. Moreover, the soil fertility in the 11-year-old orchards showed a detectable decrease. Further analysis suggested that the soil microbial biomass and enzymatic activities of the Huangguogan orchard were strongly correlated with the diameter at basal height and fine root biomass of the fruit trees and soil total organic carbon (TC) and nitrogen (TN). These findings indicate that the above-ground parts of the plants and the soil nutrient status are correlated with changes in the soil enzymatic activities and microbial community. This study highlights the finding that management practices that help to increase plant vigour and microbial biodiversity should be a focus of slope orchards in later reclamation stages.