This paper studied changed properties of soils in the typical ecotone of Duolun County,Inner Mongolia for two years.Results showed that the content of clay decreased with increased sandy desertification on grassland.Soil moisture decreased significantly,especially within 20 cm of the soil surface(P0.05).Soil moisture in deeper layers was higher than the upper.Soil bulk density was found to increase with depth and has a certain correlation with the degree of sandy desertification in different depths.Soil bulk density in the 30-50 cm layer was the lowest in Ⅱ stage,and in the 0-5 cm layer,the lowest in Ⅴ stage.The contents of organic matter(OM),carbon(C) and nitrogen(N) in soils decreased significantly(P0.001).The reduction in nitrogen was more rapid than carbon,which led to an increase in the C/N of soil.This indicted that the nitrogen supplying to plant was insufficient.The positive correlation between granular composition and nutrient elements was significant.The correlation between clay and N was similar to those between clay and C and between C and N.Therefore the reduction in fine particles resulted in the significant reduction in N.The correlations among soil bulk density and the contents of carbon,nitrogen and clay showed that the finer particle,the higher content of organic matter and the lower soil bulk density.This indicted an improvement in soil stability,especially in the 5-10 cm layer(P0.001).