The Loess Plateau is a region where soil erosion is the most serious in China. The serious soil erosion in the plateau results directly in the reduction of land quality and the occurrence of desertified landscapes. The area of soil erosion in the Loess Plateau is 4.03×105 km2, and it is estimated that the annual loss of topsoil in the plateau is 5.0×109 t. In the plateau land degradation occurs, the productivity of lands and the area of usable lands are reduced, and the ecosystems are degenerated due to the serious soil erosion caused by the irrational exploitation and utilization of water and land resources. Some study results reveal that the area of water-eroded desertified lands in the plateau is currently 2.705×105 km2 and occupies 42.89% of the total area, in which the area of seriously water-eroded desertified lands occupies 11.025%, and the water-eroded desertification becomes more and more serious. In this paper, the formation causes and the occurrence mechanism of water-eroded desertification are researched. The results show that the water-eroded desertification is still in development and can not be reversed due to the severe natural environment although the situation has been improved in some regions. Regionally, the water-eroded desertification becomes more serious northward and westward. The water-eroded desertification is induced and promoted by extensive human activities, such as the excessive reclamation and grazing as well as the mining and urban construction. Therefore, some measures are put forward for controlling land desertification, they are to enhance the dynamics of ecological regeneration, reduce the water erosion by building some projects and improving farming techniques, work out the feasible policies, regulate the current social and economic development modes, etc.