Abstract:[Objective] The middle and upper reaches of the Yarlung Zangbo River basin is a major nature ecological reserve in China, which is also one of the regions with the most serious eolian landform development. It is significant to monitor and identify land desertification for ecological protection and restoration of the basin, which can also provide key support for the construction of national ecological security barriers. [Methods] This study employs an improved desertification differential index method based on the three-dimensional space of vegetation, surface reflectance, and soil moisture (NDVI-Albedo-Wet) to analyze the spatiotemporal evolution of land desertification in the research area over the past 30 years. Based on this, attribution analysis of land desertification is conducted from the perspectives of temporal changes and spatial differentiation using principal component analysis and geographical detector methods, respectively. [Results] The results indicate that the degree of land desertification in the middle and upper reaches of the Yarlung Zangbo River basin has been alleviated, but there are still local exacerbations. Specifically, the total area of land desertification has decreased from 34800 km2 in 1990 to 16700 km2 in 2020, but the degree has increased in some areas, concentrated in the western part of the study area, such as Saga and Jilong, and the southeastern parts, such as Kangma and Qiongjie Counties. The spatial distribution of land desertification exhibits a strip-like pattern along the main river channel from west to east, concentrated on gentle slopes, moderate slopes, grasslands, and unused land. Over the past 30 years, the reversal of land desertification in the study area has been primarily influenced by human activities, with the principal contributing factors accounting for 59.1%. The spatial differentiation of land desertification has shifted from the dependence on natural geographical factors such as elevation and wind speed in 1990 to the synergy influence of multiple factors including natural and socio-economic factors in 2020, with the impact of various driving factors on the spatial distribution of land desertification exhibiting a dual-factor enhancement and non-linear increase. [Conclusion] It is suggested to further strengthen the ecological restoration of the source area, as well as enhance sand source management and vegetation cultivation within a 10-kilometer radius of both the left and right banks of the river.