Soil microorganisms play an important role in nutrient cycling in forest ecosystems, so it is of great significance to investigate the changes in soil microorganisms with forest age. We collected soil at different soil depths (0-10 cm, 10-20 cm, and 20-30 cm) to investigate the microbial phospholipid fatty acids (PLFAs) and the effects of soil properties and enzyme activities on soil microbial PLFAs. The results showed that: (1) with the increase of forest age, the soil total PLFAs, fungi, and bacteria content showed an increasing and then decreasing trend. (2) Soil fungi and bacteria showed significant positive correlations with soil organic carbon, β-glucosidase activity, acid phosphomonoesterase activity, phenol oxidase activity, peroxidase activity, and microbial biomass phosphorus. (3) Soil total nitrogen, available phosphorus, organic carbon, and total microbial PLFA contents in the 30-year-old Castanopsis hystrix plantation forest were higher than in the 6-year-old forest, which indicated that soil quality showed a trend of stable recovery after a longer period of community succession. However, it should also be noted that the microbial PLFAs declined as the stand age increased to 10 years, and fertilizers should be reasonably applied to improve soil fertility in future C. hystrix plantation forests.