Abstract: Rocky desertification is widely distributed in karst areas of Southwest China, especially in Guizhou Province, posing a serious threat to the local ecological environment security. In order to clarify the internal relationship between the bedrock weathering and the degree of rocky desertification, the authors in this paper comprehensively analyzed the content of major and trace elements and the law of migration and evolution, mineral composition characteristics, and the ability of weathering and soil formation for the rocky desertification sections with different desertification degree in Guizhou Province. The results show that the soil material in rocky desertification area is the result of soluble material dissolution in carbonate rocks and the continuous accumulation of acid insoluble material in situ. The rocky desertification sections with different degrees are in a high degree of weathering, and mineral weathering trend in sections, also shows that the higher the degree of rocky desertification, the higher the degree of soil layer weathering phenomenon. The development of rocky desertification is closely related to the migration model of elements in the process of bedrock weathering. The higher the content of soluble elements in carbonate bedrocks, the less the residual soil material produced by bedrock weathering, and the higher the development degree of rocky desertification. The analysis of the geochemical characteristics of bedrock and ecological geological effects of weathering in the rocky desertification area could provide some references for the study of the genetic mechanism of rocky desertification, and is also of great significance to the rocky desertification controlling and the promotion of the sustainable development of regional economy.