Karst soil rocky desertification is not only a geo-ecological disaster induced by Karst geomorphy, but also a critical factor restraining social and economic development of Southwest China.Soil mechanical composition, physical features, chemical propert ies, microbial feature and chemical composition of soils were measured for studying the Karst rocky desertification.The results indicate that fine soil particles decrease propressively with soil erosion, leading to disappearance of surface soil layer and replacement of a sand layer.The absence of weathering parent material between soil and rocks makes calcareous soil unstable.Soil erosion at the rock-soil interface is a distinct character.Soil texture tends to be desertified.As a result, soil organic matter and nutrients in the surface soil layer reduce progressively and so do the soil's nutrient and moisture retention and functional diversity of the soil microbial communities.Soil formation is at the stage of chemical erosion and sand deposition.It could be concluded that rocky desertificat ion is the final result of a vicious cycle of social economic stress and environmental deterioration.