With the accelerating process of urbanization, the problem of environmental protection is becoming more and more prominent. Strengthening the construction of ecological civilization has increasingly become the focus of urban development. Therefore, it is particularly important for rapid monitoring of changes in urban ecological environment. Landsat TM/OLI remote sensing images of 1995, 2005 and 2015 were chosen as the main source of data. Four ecological factors were calculated as evaluation indicators, namely greenness, wetness, dryness, and heat. Principal component analysis was used to derive the remote sensing ecological index (RSEI). The ecological changes in Wanjiang city belt in recent 20 years were analyzed objectively, rapidly and quantitatively. The results show that the changes of ecological environment quality in Wanjiang city belt in 1995-2015 years are “down then up”, with an overall rising trend. The RSEI dropped from 0.710 in 1995 to 0.683 in 2005, and then rose to 0.728 in 2015 with a total increase of 2.54%. During 1995-2015, the proportion of ecologically deteriorated areas decreased from 20.03% to 14.65%, with a decrease of 26.86%. While the proportion of ecologically improved areas increased from 21.87% to 29.39%, with an increase of 34.39%. The ecologically deteriorated areas are mainly concentrated in the expanding cities and regions along the Yangtze River. The areas with improved ecological environment mainly concentrate on the areas with vegetation cover, environmental regulation and greening effect. Overall, urban ecological quality is most closely related to vegetation cover (NDVI) and impervious building area (NDBSI). With the development of urban expansion, we should strengthen the construction of ecological civilization, pay attention to environmental protection, increase the afforested area and realize the sustainable development of the city.

Key words：the Wanjiang City Belt; RSEI index; urban ecology; change detection; principal component analysis