Abstract: To clarifying the recovery mechanism of alpine grassland actual net primary productivity on the Qinghai-Xizang Plateau,this study firstly analyses the spatial, temporal and vertical changes of actual net primary productivity, then evaluate the relative contributions of climate change and anthropogenic activities to actual net primary productivity by multi-source data fusion,and finally combined the structural equation model to further explain the recovery mechanism. The results show that actual net primary productivity increased significantly from 2001 to 2020, and is concentrated in the altitude range of 3000～4000 m; 83.44% of the actual net primary productivity of grassland increased in the past 20 years, of which 71.29% is dominated by anthropogenic activities; Temperature and soil nutrients are the most important direct effects on the actual net primary productivity, and the meteorological factors also participated in soil nutrient cycling by regulating soil pH, which in turn promoted the increase of actual net primary productivity. The results provide the scientific basis for the scientific use and protection of alpine grassland on the Qinghai-Xizang Plateau.

Key words: grassland net primary production, multi-source remote sensing data, climate change, anthropogenic activities, driving mechanism