Abstract: A faster speed of urbanization causes a series of problems to ecological environment which is the material base for human’s survival and development. However, the changes of the ecological environment can be evaluated by remote sensing technology in a quick and quantitative manner. Landsat remote-sensing images in 2000, 2009 and 2017 were used to extract four evaluation indexes, namely, humidity, greenness, dryness and heat. The principal component analysis was also used to calculate RSEI (Remote Sensing Ecological Index) to carry out quantitative analysis and dynamic monitoring evaluation on the ecological environment change of Yongjiang River Basin during the 17 years. Results show: (1) The ecological environment in Yongjiang River Basin in 2000-2017 declined generally. RSEI in 2000, 2009 and 2017 was 0.724, 0.651 and 0.687 respectively. The total decline over the past 17 years was 5.11%. (2). The ecological environment in Yongjiang River Basin in 2000-2009 deteriorated gradually but improved in 2009-2017; The area that became worse obviously is 1 392.49 km ², accounting for 29.63% approximately while the area that became better obviously is 699.1 km ² only, accounting for 14.88% only. Generally speaking, the old urban area becomes better while the urban pheripheral area of cities become worse; forest, farmland, etc. maintain stable. (3) Among the four indexes, greenness exerts significant influence and the influence of heat affected by architecture is most potential, which implies that the reduction of ecological environment quality is related to the increase of impervious surface and the reduction of green landscape.