【Objective】Microbial necromass carbon plays a significant role in the global carbon cycle and is a key contributor to soil organic carbon. Its importance stems from its stability, which is crucial for carbon protection and long-term carbon storage in soils. Within microbial necromass carbon, fungal necromass carbon (FNC) and bacterial necromass carbon (BNC) are two main components, and research has shown that FNC is more stable than BNC. Therefore, a higher proportion of FNC relative to BNC, expressed as the FNC/BNC ratio, is often considered indicative of greater microbial necromass carbon stability. However, despite the recognition of this relationship, the global distribution patterns of microbial necromass carbon stability and the factors influencing these patterns remain unclear due to a lack of large-scale observational data. Addressing this gap is essential for advancing our understanding of the mechanisms behind soil carbon cycling and protection.【Method】To address these uncertainties, this study employs a combination of meta-analysis and machine learning techniques to analyze microbial necromass carbon stability on a global scale. Meta-analysis allows for the synthesis of findings from multiple studies to produce more robust conclusions, while machine learning enables the identification of complex patterns in large datasets. Together, these methods offer a powerful approach to uncovering the spatial distribution of microbial necromass carbon stability and its driving factors. The study specifically examines the relationship between FNC/BNC ratios and various environmental variables, including soil nutrient levels (such as soil organic carbon, total nitrogen, and total phosphorus) and climatic factors (such as annual mean temperature and evaporation). By analyzing data from different ecosystems and climatic zones, the study aims to clarify the global patterns of microbial necromass carbon stability and the key factors influencing it.【Result】The results showed that the global average stability of microbial necromass carbon was 3.09. Among different ecosystems, forests had the highest average value (3.94), while deserts had the lowest (1.09). In terms of climate zones, the highest average value was found in the polar regions (4.14), and the lowest in arid climate zones (1.69). In different aridity index regions, the stability of microbial necromass carbon was lowest in extremely arid areas (0.75) and highest in semi-humid regions (3.77). Also, microbial necromass carbon stability exhibits distinct characteristics across different regions.【Conclusion】Overall, microbial necromass carbon stability tends to be lower under conditions of higher annual mean temperature or greater annual evaporation, indicating a negative correlation between climatic conditions and microbial necromass carbon stability. Soil organic carbon, total nitrogen, and microbial biomass nitrogen were identified as key regulators of microbial necromass carbon stability, with positive correlations to its stability. Moreover, annual mean temperature and evaporation indirectly affected microbial necromass carbon stability by influencing the levels of soil organic carbon, total nitrogen, and total phosphorus. The study highlighted the global spatial distribution of microbial necromass carbon stability and the major driving factors behind it. These findings provide valuable theoretical support for developing soil management strategies that focus on protecting and enhancing organic carbon based on the stability of necromass. Such strategies can help maintain and improve soil health, carbon sequestration, and ecosystem functioning in the face of changing environmental conditions.