Abstract: In order to timely monitor the ecological environment changes during the development of water energy and coordinate the relationship between hydropower development and ecological environmental protection, Landsat TM/OLI images in 1987, 2004 and 2015 were selected according to the timeline of Qingjiang hydropower cascade development. Four evaluation indexes, namely, modified adjusted soil vegetation index (MASVI), wet index (WET), land surface temperature (LST) and normalized difference soil index (NDSI), were extracted to represent the four aspects of greenness, humidity, heat and dryness. A new remote sensing ecological index (RSEI) was generated using principal component analysis to evaluate the ecological environment of Qingjiang hydropower development zone. Results show that:(1) The RSEI of the middle and lower reaches of the Qingjiang River in 1987, 2004 and 2015 were 0.443, 0.664, and 0.515, showing a trend of first rising and then declining. (2) The ecological environment improvement areas are mainly distributed in the low hilly areas and flat plain areas, while the ecological environment degraded areas are mainly distributed in the water conservancy hubs and their affiliated reservoir areas, the Karst mountains along the coast, and the hilly areas where the Qingjiang River afflux into the Yangtze River. (3) The ecological environment of Qingjiang hydropower development area is most closely related to the MASVI and the NDSI. The average correlation of the 3 years between ecological environment and these two indexes is 0.879 and -0.916, respectively. Improving vegetation coverage and controlling bare and dry surface are the keys to the environmental restoration of hydropower construction areas.