The Horqin Steppe is one of the regions that has suffered seriously from desertification in North China. According to the fieldwork investigation and the remotely-sensed data processing of wide scope, of 146, 700km2, the desertified land has expanded from 22, 730km2 in late 1950s to 57, 980km2 in 1976 and to 71, 680km2 in 1988. Desertification caused the decline of land productivity and the degeneration of the ecological environment, which restricted the subsistence and sustainable development in the region. To combating it, many projects have been carried out for many years so that about 4, 500km2 of desertified land has been remedied only in the south part of the Horqin Steppe Region by the late 1980s, and much more after that. The theory and practice of combating desertification have made good progress. In this paper, based on case study, we monitored and evaluated the effective measures to deal with desertification in the region and reach the conclusion that desertification is land degradation resulting mainly from adverse human impacts on the fragile ecosystem, such as over-cultivation, over-grazing and over-collection of fuelwood. This has been caused by the rapidly increasing population and a less developed production pattern, and it could be prevented and remedied through readjusting the economic activities, improving the land management, increasing the agricultural investment and implementing the controlling measures.