Abstract: Taking the Jinsha river basin with a complex natural environment and important ecological functions as a research area, an evaluation index system was constructed from two aspects of natural environment and human activities, and a spatial principal component analysis model was used to quantitatively evaluate the ecological vulnerability of the Jinsha river basin from 2005 to 2015. The evaluation results were graded and counted, and then the distribution characteristics and change trends of its ecological vulnerability were obtained. The results showed that the ecological fragility in the Jinsha river basin was significantly different, the upstream ecological environment was better, the middle reaches was second, the downstream was more fragile, and the areas river flow was less vulnerable than the two banks of the valley; The overall ecological environment in the river basin was at a medium level, and the proportions of vulnerability levels from high to low were mild fragile, moderate fragile, potential fragile, severe fragile, and extreme fragile; During the three study periods from 2005 to 2015, the comprehensive index of ecological vulnerability （EVSI） of the Jinsha river basin were 2.53, 2.55 and 2.38, respectively, which firstly increased slightly and then decreased, coupled with the continuous reduction of extremely vulnerable areas, and the overall ecological environment had improved.

Key words: ecological vulnerability, Jinsha river basin, spatial principal component analysis, GIS, RS