Abstract: The Qinghai-Tibet Plateau, recognized as the world’s highest and most extensive plateau, serves as a critical ecological security barrier for both China and Asia, feeding major river systems including the Yellow River and the Yangtze River. Its alpine wetlands, distinguished by high biodiversity and abundant water resources, play an important role in regional water conservation and climate regulation. Understanding the dynamics of their water yield function is paramount for sustainable water resource management and ecological protection in this fragile environment. This study systematically elucidates the spatiotemporal dynamics of water yield in alpine wetlands across the Qinghai-Tibet Plateau from 2000 to 2020, along with its underlying driving mechanisms. Utilizing remote sensing imagery from 2000, 2010 and 2020, we analyzed areal changes and spatial transitions among different wetland types, quantitatively assessed water yield variations using the water balance equation, and further employed a geodetector model to explore the influence mechanisms of both natural factors (precipitation, vegetation cover, wetland type) and anthropogenic factors (livestock carrying capacity). The results revealed that alpine wetland types on the Qinghai-Tibet Plateau are dominated by meadow wetlands and mudflats. From 2000 to 2020, the total wetland area gradually decreased, with meadow wetlands and mudflats exhibiting the largest reductions, decreasing by 4.31×10⁴ hm² and 2.24×10⁴ hm², respectively. The mean annual water yield of alpine wetlands was 215.92 mm, exhibiting relatively low inter-annual variability but pronounced spatial heterogeneity, characterized by a distinct east-high and west-low pattern. Notably, water yield capacity varied significantly by wetland type, with peat wetlands demonstrating the highest capacity, followed by meadow wetlands and shrub wetlands, while salt marshes and mudflats showed the lowest. Furthermore, natural factors predominantly governed water yield in alpine wetlands. Precipitation was identified as the primary driver influencing the spatial distribution, followed by vegetation coverage. Importantly, the interactive effect between precipitation and wetland type exerted a stronger influence on water yield than any single factor, highlighting the complex, coupled nature of these environmental controls. Anthropogenic factors, while contributory, demonstrated comparatively weaker effects than natural drivers. Overall, this study systematically clarifies the spatiotemporal patterns and multi-factor driving mechanisms of water yield across different alpine wetland types on the Qinghai-Tibet Plateau over the past two decades. These findings not only advance the scientific understanding of water-related ecosystem services in high-altitude wetland ecosystems but also provide critical theoretical support for the rational utilization and sustainable management of water resources on the Qinghai-Tibet Plateau.