Abstract: According to the definition by the International Convention of Desertification Control in 1994, the present situation of the desertification in Eastern Inner Mongolia is investigated and classified. The distribution and types of harmfulness of the desertification are discussed. It is concluded that three types of desertification occur in the region, i. e. sandy desertification, soil salinization and wet blasted desertification. The desertification covers an area of 148 521 km², accounting for 54.76% of the total studied area. The increasing desertification has caused a series of environmental problems such as grassland deterioration, sand storm, groundwater level lowering, etc.