To better predict responses of soil nitrogen mineralization to the changes of precipitation variations in plantation ecosystem, a throughfall reduction experiment including 50% of throughfall and natural rainfall (control) treatments was conducted in Pinus massoniana plantation in southern subtropical China. Soil nitrogen mineralization rates were measured by closed-top tube incubation method. The soil nitrogen mineralization of Pinus massoniana plantation was dominated by ammonification. The throughfall reduction treatment significantly decreased soil net nitrification rate, soil water content, pH, soluble organic carbon, peroxidase and AMF PLFAs. Conversely, the throughfall reduction treatment significantly increased soil net ammonification rate, NO₃^--N N-acetyl-glucosidase and leucine-amino-peptidase, which varied with different seasons and the soil layers. Soil net ammonification rate was significantly negatively correlated with N-acetylglucosaminidase. The variable that had the greatest influence on the soil net nitrification rate was the soil water content, followed by β-glucosidase, fungal PLFAs and Bacteria/Fungi ratio. The results indicated that the short-term experimental throughfall reduction significantly altered soil physichemical properties, soil net ammonification rate and soil net nitrification rate, which could further affect the tree growth and nutrient uptake of Pinus massoniana plantation.