Abstract: Based on the remote sensing image data of 2000, 2010, and 2020, the four core indicators of green degree index (NDVI), humidity index (WET), dryness index (NDBSI), and heat index (LST) were extracted through Landsat series satellite images, and the remote sensing ecological index (RSEI) was constructed using the principal component analysis to comprehensively evaluate the land ecological quality of Suijiang County, Yunnan Province, and reveal its spatial and temporal evolution characteristics and driving mechanisms. The results showed that,from 2000 to 2020, the average RSEI of Suijiang County decreased from 0.61 to 0.47, and the ecological quality showed a trend of overall degradation. After 2010, the vegetation restoration effect of Suijiang County was remarkable, and the green degree index continued to increase. The expansion of construction land and the dry and hot climate led to a significant increase in the dryness index and a continuous decline in the humidity index. The ecological degradation of Suijiang County was concentrated in the Jinsha River coastal areas and the areas with the expansion of construction land, while the high-altitude areas with good vegetation protection still maintained high ecological quality.

Key words: remote sensing ecological index, land ecological quality, green degree index, humidity index, dryness index, heat index, Suijiang County