Abstract: Utilizing data from MODIS remote sensing imagery spanning 2001 to 2023, four indicators of greenness, humidity, heat, and dryness were quantitatively examined．Principal component analysis method was applied to construct remote sensing ecological evaluation index（RSEI）．Quality status and evolution trend of ecological environment in the western plateau of Sichuan Province（referred to as the Western Sichuan Plateau）were explored and interpreted, and in-depth evaluation and analysis of ecological situation in the region was conducted．Results indicated that greenness and humidity had a promoting effect on quality of ecological environment．Overall ecological quality of research area showed a trend of first increasing and then decreasing．The RSEI value reached its highest point in 2013 and then showed a slight downward trend, but overall ecological environment quality showed a slight upward trend．The area of significant and slight deterioration of ecological environment from 2001 to 2023 accounted for less than 0.01% of total area, while the area of slight and significant improvement accounted for 56.82%．Overall, ecological environment quality of Western Sichuan Plateau has gradually improved from 2001 to 2023．