Abstract: This paper studies the causes of grassland desertification from basin analysis and sedimentology perspective. The Xilin Gol Steppe covers above Erlian Basin directly. Various depressions of this basin features a complete life cycle:Evolution of its synsedimentary structure terminated at the ending period of the basin basement subsidence deceleration stage while sedimentation filling evolution ended in the lake-shrinking-plain forming stage, then was in a slow rising state. The evolution processes and results of this basin caused a wide range development of the lakes regressive systems tract at the top of the filling sequence-river and delta sand body with huge thickness and low degree of consolidation. Human factors and meteorological factors destroyed the grassland vegetation, exposing these huge sand bodies to the surface, resulting base of steppe degradation and desertification. Obviously, the vulnerability of the geological environment is the determining factor of the vulnerability of the ecological environment in this case. Therefore, desertification in the Xilin Gol Steppe is a kind of geological hazard. Without immediate and effective controls, a large-scale of desertification may occur. This type of desertification is common in North China, North West and North East China. The paper will provide a basis for the treatment of this particular kind of grassland desertification.

Key words: grassland degradation, land desertification, geological environment vulnerability, Xilin Gol Steppe, basin snalysis, Erlian Basin