[目的] 分析三江源植被覆盖变化趋势，掌握三江源生态环境状况，为三江源后期生态建设项目的宏观布局和实施提供科学依据。[方法] 基于MODIS-NDVI，DEM及气象数据，借助最大合成法(MVC)、趋势分析、Hurst指数等方法从多个角度，综合分析2001—2020年三江源植被覆盖时空演变特征及未来发展趋势，并结合偏相关分析和多元回归残差分析法探讨气候变化和人类活动对植被覆盖的响应特征。[结果] ①近20 a来三江源植被覆盖呈现显著上升趋势，增速为2.1%/10 a；空间上整体呈现“东南高，西北低”，从东南向西北呈阶梯式逐渐递减。②三江源植被覆盖整体表现为上升趋势，上升面积占74.59%，下降面积占25.41%，具体表现为东北部以及西北部显著上升，曲麻莱南部、杂多北部和甘德西南部下降。③三江源植被覆盖未来变化的反向特征比同向特征更明显，持续改善面积占29.22%，改善到退化的面积占45.54%。④气温和降水对三江源植被覆盖都呈正面影响，且降水是主要驱动因子。⑤人类活动对三江源植被覆盖影响呈显著增强趋势，且以积极影响为主，主要分布在黄河流域东北部、长江流域通天河南侧和澜沧江流域东南部。[结论] 三江源是中国生态安全的重要区域，植被覆盖受气候和人类活动影响大，需要加强区域生态保护治理和生态维持。
[Objective] The change trend of vegetation cover in the Three-River headwaters region, and its ecological environment were analyzed, in order to provide a scientific basis for the macro layout and implementation of ecological construction projects in the future. [Methods] Based on MODIS-NDVI, DEM, and meteorological data, the spatio-temporal evolution characteristics and future development trend of vegetation cover in the Three-River Headwaters region from 2001 to 2020 were comprehensively analyzed from multiple perspectives by using the maximum-value composite procedure (MVC), trend analysis, the Hurst index, and other methods. The responses of climate change and human activities to vegetation cover were analyzed by combining partial correlation analysis and multiple regression residual analysis. [Results] ① The vegetation cover of the Three-River headwaters region has increased significantly over the past 20 years, with a growth rate of 2.1%/10 yr. Overall, vegetation cover was high in the southeast and low in the northwest, and gradually decreased from southeast to northwest. ② Vegetation cover in the Three-River headwaters region increased over time, with the area of increasing vegetation cover accounting for 74.59%, of the total area, and the area of decreasing cover accounting for 25.41%. The vegetation in northeast and northwest areas increased significantly, and the areas in South Qumalai, North Zaduo, and Southwest Gande decreased. ③ The reverse characteristics of future changes in vegetation cover in the Three-River headwaters region were more obvious than those in the same direction. The area of continuous improvement accounted for 29.22% of the total area, and the area of improvement to degradation accounted for 45.54%. ④ Temperature and precipitation had positive impacts on vegetation cover in the Three-River headwaters region, and precipitation was the main driving factor. ⑤ The impact of human activities on vegetation cover in the Three-River headwaters region increased over time, and the positive impact was mainly located in the northeast Yellow River basin, south of the Tongtian River in Yangtze River basin, and the southeast part of the Lancang River basin. [Conclusion] The Three River headwaters region is an important area for ecological security in China. Vegetation coverage is greatly affected by climate and human activities. It will be necessary to strengthen regional ecological protection and ecological maintenance.