【Objective】 Extracellular enzymes in soil play a crucial role in mediating the ecosystem's responses to environmental drivers, and their stoichiometry can be used to assess the resource limitation for microorganisms. The conversion from pure forest plantations to mixed forest plantations is an important approach to achieve sustainable forest development. The current study on ecosystem responses to forest conversion has predominantly concentrated on soil nutrients, carbon (C) sequestration capacities, timber productivity metrics, and silvicultural landscape attributes. However, the effects of this conversion on extracellular enzymes and their stoichiometric characteristics in soil remain poorly understood. 【Method】 Here, the 5-year-old mixed forests of Prunus persica ‘Atropurpurea’ + Malus × micromalus, Cunninghamia lanceolata + Phoebe zhennan + P. persica ‘Atropurpurea’ and Cinnamomum camphora + Metasequoia glyptostroboides as well as pure forest plantation soil of E. grandis were investigated. All forest plantations were recently constructed after clear-cutting the E. grandis plantations. It was determined the effect of mixed forests on soil physical and chemical properties, microbial biomass, extracellular enzymes, and their stoichiometric characteristics. Moreover, the correlation between soil extracellular enzymes and stoichiometry with various soil properties was analyzed, and the main controlling factors affecting the extracellular enzymes and stoichiometry in soil were explored. 【Result】 The results showed that: (1) The three mixed forests increased β-1, 4-N-acetylglucosaminidase and l-leucine aminopeptidase activities, but decreased that of β-1, 4-glucosidase and acid phosphatase activities in soil. (2) The vector length of extracellular enzymes ranged from 0.68 to 0.88, while the vector angle ranged from 72.59° to 81.18°, indicating that microorganisms were co-limited by C and phosphorus (P) in all the forest plantation soils. (3) The three mixed forest plantations reduce microbial C and P limitations by increasing organic C, total nitrogen (N) content, pH, microbial biomass C: N ratio in soil, and C: P and N: P ratios in soil. However, the microorganisms were still co-limited by C and P. Therefore, in the early stage of mixed forest plantation construction, organic and P fertilizer can be applied to reduce resource limitations of soil microorganisms in the study area. (4) Total N and microbial biomass N were the key controlling factors influencing extracellular enzyme activity and enzyme stoichiometry in all the forest plantation soils. 【Conclusion】 Collectively, these findings suggest that the conversion of pure forest plantations to mixed forest plantations alleviates the microbial C and P limitations in soil. Notably, extracellular enzymes and their stoichiometric characteristics in soil are influenced by interactions among vegetation, soil properties, and forest microclimate factors. Thus, future studies should prioritize analyzing how mixed forest plantations affect these parameters through plant diversity assessments (e.g., tree and understory vegetation), and understory microclimate monitoring.