Phosphate-solubilizing microorganisms are the key factors in driving phosphorus (P) cycle in forest soil, especially in subtropical forest soil where P is scarce. Although microorganisms are sensitive to environmental changes, it is still unclear the changes in microbial function and their effects on soil P cycling in response to nitrogen (N) deposition. In this study, a long-term N deposition experiment platform was established in the Castanopsis Carlesii natural forest at the National Research Station of Forest Ecosystem and Global Change in Sanming, Fujian Province. Through the 16S rRNA and ITS-based high-throughput sequencing and PICRUSt functional prediction methods, we investigated the effects of N addition on the community and functional potential of phosphate-solubilizing microorganisms in the soil. The results showed that the N addition significantly increased the available N content of the soil, but significantly decreased Resin-P, NaHCO₃-P, and TPo, indicating that N deposition altered the soil nutrient balance and aggravated soil P limitation. In addition, N addition significantly decreased the abundance of phosphate-solubilizing bacteria such as Rhizobia and Burkholder, while increased the abundance of phosphate-solubilizing fungi such as Penicillium and Aspergillus. The prediction analysis of the function of phosphate-solubilizing microorganisms by PICRUSt also further revealed 15 genes that are capable of encoding phosphatases, the abundance of genes encoding enzymes such as acid phosphatase, alkaline phosphatase, and phytase increased significantly after N addition. In conclusion, N addition induced P limitation in this subtropical Castanopsis carlesii forest. The increased phosphate-solubilizing fungi and the associated increases in phosphatase genes might be beneficial to organic phosphate mineralization, which may act as the main microbial mechanism driving soil P transformation in Castanopsis carlesii natural forest under N deposition.