Global climate change is altering temperature and precipitation patterns, which profoundly affect soil organic carbon (SOC) dynamics, especially in sensitive high-elevation ecosystems of the Qinghai-Xizang Plateau (QXP). SOC consists mainly of particulate organic carbon (POC) and mineral-associated organic carbon (MAOC), each responding differently to environmental changes. However, previous studies in high-elevation ecosystems has often overlooked how these two SOC pools react asynchronously to varying conditions, limiting our understanding of SOC stability and carbon cycling under climate change. This study examines how POC and MAOC vary along aridity gradients on the QXP and assess their implications for SOC stability and carbon sequestration. Soil samples were collected from 220 sites at two depths (0-20 cm and 20-40 cm), across arid, semi-arid, semi-humid, and humid regions. SOC increased roughly 5 times from arid to humid regions (about 13.18 g center dot kg-1 and 69.22 g center dot kg-1), and SOC stability was only 0.57 in semi-arid region and lower than other regions. Crucially, POC and MAOC responded asynchronously to environmental factors. NDVI and climate variables drove rapid POC gains in semi-arid regions, whereas in semi-humid and humid regions rising vegetation cover triggered steep MAOC accumulation. These findings highlight that SOC pools respond differently to aridity: labile POC tracks moisture-driven vegetation increases in transitional semi-arid and semi-humid regions, while stable MAOC accumulates faster under wetter conditions. Our study reveals the critical role of asynchronous responses between POC and MAOC in controlling SOC content and stability on the QXP, with implications for predicting C-cycle feedbacks under climate change.