【Objective】Cunninghamia lanceolata is a significant timber species in subtropical China with a long cultivation history. However, persistent monoculture management has triggered multiple ecological issues, including soil nutrient depletion, biodiversity loss, and declining forest productivity. To enhance ecological functions and economic returns while achieving sustainable development of Cunninghamia lanceolata plantations, precious tree species were introduced through interplanting and their effects on soil chemical properties and microbial communities were investigated.【Method】Soil samples were collected from pure Cunninghamia lanceolata plantations (PC) and four mixed forests: Taxus wallichiana-C. lanceolata (MTC), Ormosia hosiei-C. lanceolata (MOC), Phoebe chekiangensis-C. lanceolata (MPC), and Houpoea officinalis-C. lanceolata (MHC) in Qingyuan Forest Farm, Zhejiang Province. Soil chemical properties were analyzed via standard protocols. Microbial community composition was characterized using 16S rRNA and internal transcribed spacer (ITS) high-throughput sequencing, while co-occurrence network analysis and partial least squares path modeling (PLS-PM) were employed to decipher microbial interactions and functional linkages.【Result】(1) Interplanting significantly improved soil chemical properties. The MPC treatment increased soil pH by 11.2% (P<0.05), while the MTC treatment elevated soil organic carbon (SOC) content to 31.8 g·kg-1, a 26.2% increase compared to PC (P<0.05). The MOC treatment significantly boosted available phosphorus (AP) content by 3.96 times relative to PC (P<0.01). (2) The bacterial co-occurrence networks in mixed forests exhibited increased nodes, edges, and path lengths. Significant differences (P<0.05) were observed in degree centrality, closeness centrality, and eigenvector centrality among the treatments. Notably, the MTC treatment resulted in the highest degree centrality and eigenvector centrality within the soil bacterial co-occurrence network, indicating the formation of a more efficient and stable bacterial community structure. (3) Functional gene analysis revealed distinct metabolic pathways: PC treatment was dominated by nitrogen respiration and nitrogen fixation functions, whereas MTC and MPC treatments activated xylanoly and nitrate reduction functions, respectively. (4) PLS-PM demonstrated that soil chemical properties indirectly influenced the expression of carbon and nitrogen cycling genes by regulating key microbial taxa, such as those within the Actinobacteria phylum.【Conclusion】Interplanting valuable tree species significantly enhances the stability of Cunninghamia lanceolata forest ecosystems by optimizing soil physicochemical properties and strengthening the complexity and functional redundancy of microbial networks. The improvements in soil chemistry (pH, SOC, AP), the formation of more complex and stable bacterial co-occurrence networks (particularly under MTC), and the shift towards specific functional genes (carbon decomposition, nitrate reduction) collectively underpin this increased ecosystem resilience. Based on the superior performance in fostering stable microbial structures and activating beneficial functional genes, the Taxus wallichiana-C. lanceolata mixed model (MTC) is prioritized for future promotion in southern China. Supplementing this with interplanting Phoebe chekiangensis is recommended to synergistically optimize overall soil quality.