Scientific assessment of spatial variations in human activity intensity and their ecological impacts on the Qinghai-Tibet Plateau was essential for region sustainable development. This study selected the high-intensity human disturbance zone of the Nianchu River Basin on the Qinghai-Tibet Plateau as a case study. It utilized multi-source data, including land use status, transportation networks, nighttime lights, net primary productivity (NPP) data, and socio-economic statistics, to conduct a quantitative analysis of changes in human activities in ecologically fragile regions and their impacts on the ecological environment. The results showed that: (1) Over the past two decades, the population of the Nianchu River Basin grew rapidly, regional industrialization accelerated significantly, the transportation network evolved from a "Y-shaped" layout to a more networked structure, and land use intensity increased markedly over the past ten years, exceeding the average level of Tibet. (2) From 2000 to 2020, landscape diversity and evenness in the Nianchu River Basin increased, and the carbon sequestration and oxygen release functions were enhanced. However, landscape fragmentation intensified, and the emissions of solid waste, water pollutants, and air pollutants increased by 25.5%, 19.64%, and 95.66%, respectively, indicating heightened environmental stress. (3) The ecological environment quality of the basin exhibited a spatial pattern of "higher in the downstream and lower in the upstream," with the EEQI index ranked from highest to lowest as Jiangzi County, Sangzhuzi District, Bailang County, and Kangma County. At the township scale, the proportions of areas with excellent, moderate, and poor ecological conditions were approximately 44：31：26. (4) Variations in ecological environment quality across the Nianchu River Basin were mainly driven by the combined effects of population density, land use intensity, economic density, and road density. Among these, road density primarily affected the landscape pattern dimension, with the impact of roads on landscape fragmentation following a distance decay pattern, showing the greatest influence within approximately 250 m. Population growth and land development jointly dominated the evolution of regional ecosystem services, while increases in population and economic density mainly influenced the baseline of pollutant emissions, thereby affecting regional environmental quality.