Abstract: At present, land desertification is developing evidently in the Ejin basin and the environment of the basin is further deteriorating. The trend and cause of desertification of the Ejin basin were analyzed in the environmental geological context. The authors think that desertification of the study area is controlled mainly by the regional geological environment. In the Ejin basin, the decisive factor for the initiation and development of desertification is the aridization trend in northwestern China caused by the global climate change and uplift of the Qinghai-Tibet Plateau; the main type of desertification is determined by the tectonic-sedimentary setting in the basin; and the rate of desertification is affected directly by the hydrologic environment. In addition, we must realize that human activities produce a great impact on the geological environment. Because of the irrational use of land resources and water resources, human beings speed up the development of desertification.