In order to understand the changes in the soils of Chinese fir plantations at different ages, this article explores the response mechanism of soil microorganisms and enzyme activity to forest age growth, providing a basis for sustainable management of Chinese fir plantations. Five Chinese fir forests of different ages were targeted in Nanping. 16sRDNA was used to study the composition of the bacterial community, and four enzyme activity changes closely related to soil quality were analyzed. The results showed that both the microbial diversity index and OTU (Operational Taxonomic Units) increased with the increase of forest age. The soil microbial structure of young forests, middle-aged forests, near-maturity forests, and mature forests had large differences. There were 29 bacterial phylums in different ages of Chinese fir plantations. Acidobacteria and Proteobacteria were the dominant species.According to the changes of various groups and redundant analysis, Actinomycota, Verrucomicrobia, and Planctomycetes all changed significantly with age, and they were significantly related to soil dissolved organic matter and available nutrients (P<0.05). It shows that these bacterial communities are more sensitive to changes in soil quality. Soil nutrient changes affected soil enzyme activity. Sucrase had a significant positive correlation with total carbon (P<0.05) and negative correlation with available potassium (P<0.05), and a very significant negative correlation with actinomycetes (P<0.01). There was a strong correlation between urease and available nitrogen (P<0.05). Urease was strongly correlated with Proteobacteria, Chloroflexi, Actinobacteria, Nitrospirae, Bacteroidetes. In summary, soil nutrient changes have different effects on soil bacterial populations and enzyme activities. Bacterial community structure and enzyme activity can reflect changes in soil quality of Chinese fir forest at different ages. Extending the planting period of Chinese fir plantation is beneficial to the restoration of soil quality.The results of this study are of great significance for guiding the management of Chinese fir plantations.