The Hexi Corridor is a typical ecologically fragile and sensitive area, and the oases areas in the middle are the core area of the economic development of the Hexi Corridor, where the ecological problems are most serious. It is of great significance for regional ecological environment construction and sustainable development to clarify the ecological environment status and its change distribution of the Hexi oases areas. This study used remote sensing ecological distance index (RSEDI) model to generate time series of various environmental indexes of the Hexi oases areas from 1986 to 2020, based on Landsat TM/OLI images. And the changes of ecological environment were quantitatively analyzed by employing the coefficient of variation, Theil-Sen median trend analysis and the Mann–Kendall test, and Hurst index method. Results showed that: (1) The mean value of RSEDI of Hexi oases showed an increasing trend, increasing from 0.386 in 1986 to 0.405 in 2020. (2) The ecological environment changes of the Hexi oases were relatively stable, areas with low coefficients of variation accounted for 62.70%. (3) The ecological improvement areas (26.53%) were smaller than the ecological decline areas (30.83%), and areas with no change accounted for 42.62%. (4) 75.14% of areas were persistent, showing the ecological environment changes had strong sustainability. The areas with persistence and improvement accounted for 20.72%, which were distributed throughout the study area, mostly around the periphery of artificial oasis such as Shandan, and Yongchang. The areas with persistence and degradation accounted for 21.55%, which were concentrated in the middle of the study area, mainly in Sunan and Gaotai. In short, the ecological environment of the Hexi oases had been improved, but it also faced huge challenges.