Based on six indexes of greenness， humidity， heat， dryness， salinity and soil and water conservation factors， a remote sensing ecological index URSEI suitable for arid areas was constructed by using PCA， and the tem-spatial characteristics of ecological quality changes in Shiyang River Basin from 2000 to 2018 were explored by using trend analysis and Hurst persistence analysis. The findings are as follows： （1）URSEI considers salinity and soil and water conservation indicators， and the contribution rate of the first principal component is higher than 80%， integrating the main information of each indicator， which is conducive to improving the comprehensiveness of ecological quality assessment. （2） From 2000 to 2018， the URSEI in Shiyang River Basin increased from 0.288 to 0.316， which tended to improve on the whole， mainly due to the strengthening of ecological management and control policies and the implementation of water transfer projects such as Jingdian Phase II. Among them， the area of ecological quality improvement is about 10 495.75 km²， which is distributed in a belt along Jinchang City， Liangzhou District and Gulang County； The degraded area covers 2 388.50 km²， which is concentrated in the main urban area of Liangzhou District in the middle reaches， the Longshoushan mining and the middle oasis area of Minqin in the lower reaches， and there is a risk of continuous degradation in the future. （3） In the future， the ecological quality of the basin will be mainly unchanged and continuously improved， accounting for about 72.55%， but at the same time， about 2 231.25 km² of the area will develop from improvement to degradation， distributed in Minquan Township of Gulang County， Huangyang Township of Liangzhou District， Yongfengtan Township， Jiaojiazhuang Township of Yongchang County， etc.， basically corresponding to the surrounding areas of the main urban areas of each district and county. It is the main expansion area of urbanization in the future.