Abstract: For regional ecological management, it is important to evaluate the quality of ecosystems and analyze the underlying causes of ecological changes. Using the Google Earth Engine (GEE) platform, the remote sensing ecological index (RSEI) was calculated for the Lijiang River Basin in Guangxi Zhuang Autonomous Region for 1991, 2001, 2011, and 2021. Spatial autocorrelation analysis was employed to investigate spatiotemporal variations in the ecological environmental quality of the Lijiang River Basin. Furthermore, geographic detectors were used to quantitatively analyze influencing factors and their interaction effects on ecological environmental quality. The results verified that: 1) From 1991 to 2021, the ecological environmental quality of the Lijiang River Basin demonstrated significant improvement. The area with good and excellent ecological environmental quality in proportion increased by 19.69% (3406.57 km²), while the area with fair and poor ecological environmental quality in proportion decreased by 10.76% (1860.36 km²). 2) Spatially, the ecological environmental quality of the Lijiang River Basin exhibited a pattern of low quality in the central region and high quality in the periphery. Specifically, poor ecological environmental quality characterized the Guilin urban area, Pingle County, and Lingchuan County. 3) From 1991 to 2021, a significant positive spatial correlation was observed in ecological environmental quality of the Lijiang River Basin. Areas with high-high agglomeration were predominantly forests and grasslands, indicating good ecological environmental quality, whereas areas with low-low agglomeration were dominated by cultivated land and construction land, indicating poor ecological environmental quality. 4) Annual average precipitation and temperature exerted the most significant influence on the ecological environmental quality of the basin, and their interactions with other factors had the great influence. This study aimed to enhance understanding of the evolution of the ecological environment in the Lijiang River Basin of Guangxi Zhuang Autonomous Region and provide scientific guidance for decision-making and management related to ecology in the region.