Abstract: The Ganfu Plains irrigation area is the largest water diversion irrigation area in Jiangnan and the largest irrigation area in Jiangxi Province. It is considered a typical "human-society-nature" composite ecosystem. To evaluate the ecological environment quality change of Ganfu Plains irrigation area from 2002 to 2021, the remote sensing ecological index (RSEI) was constructed by integrating four indicators of NDVI, WET, NDBSI and LST with the principal component analysis method. The Landsat TM/OLI remote sensing image data in 2002, 2008, 2015 and 2021 were used. The results showed that the ecological environment of Ganfu Plains irrigation area continued to improve from 2002 to 2021. The mean value of RSEI increased from 0.477 to 0.552, with an increase of 15.71%. NDVI and LST were the most significant influencing factors on ecological quality. The RSEI level of the irrigation area was mainly at the medium level. In the past 20 years, the area of excellent and fine ecological quality grades continued to increase with a rate of 48.37%.The most prominent improvement was in the east bank of Fuhe River and Jinxian County. Because of urban expansion and hydrometeorological drought, areas with deteriorating ecological environment quality were mostly distributed in the main urban areas, agricultural areas and coastal areas of rivers and lakes. Therefore, whether to coordinate climate change and ecological environment protection while modernizing irrigation areas was the key to achieve sustainable development in irrigation areas. The research results reflected the changes in the ecological environment quality of the Ganfu Plains irrigation area, and provided theoretical reference and scientific basis for regional ecological environment governance and protection.