The two periods of Landsat TM/ETM⁺ images in 1990 and 2000 are used to dynamically monitor the ecological environment of Dingxi, Weiyuan, Longxi, and Tongwei counties. The background data are obtained through screen visual interpretation. The construction, traffic, and mining land increase by 14.97%. The farming land increases by 8.02%. The woodland increases by 11.23%. The bare land, which is suitable for forest and grassland, and floodplain land decrease correspondingly. In the later 10 years, some measurements are carried into execution, for example, small basin integration control, transferring from cultivated land to forestland and grassland, the balance between grass and animal, and rotation grazing and closing of vegetation, which are results of the rationalization of land use and land cover. But there still consists of some problems such as low land use rate, higher ratio of agriculture land, low ratio of stockbreeding land, low ratio of the trees surviving.