Abstract: Based on the study on the distribution characteristics of Cd for 19 weathering profiles in the karst areas of Guizhou, China, this work preliminarily revealed the enrichment mechanisms of Cd and the restrictive factors of Cd contents in soils developed on Cd-poor carbonate rocks.The main conclusions are as follows: ① Soils derived from Cd-poor bedrocks can also contain obvious enrichment or even supernormal enrichment phenomenon of Cd, and the summit content of Cd is usually located at the bottom of the soil layer(i.e., T1).② Cd generally preferentially occurs in acid-insoluble phase in bedrocks, and on the other hand, owing to very low mass percentage of acid-insoluble residues in bedrocks, the proportion of Cd of acid-soluble phase in the bulk rocks still has an abnormal advantage.Thus, on the basis of Cd-rich acid-insoluble phase in bedrocks, combined with the contribution of Cd from acid-soluble phase in bedrocks, it creates a fact that Cd is universally rich in soils in the karst areas.③ The content of Cd in soils is not directly related to its content in bedrocks or acid-insoluble residues of bedrocks, and it is constrained by the content of Cd in acid-insoluble residues of bedrocks, the mass percentage of Cd of acid-soluble phase in the bulk rock and the loss rate of Cd in T1 together.The optimum conditions conducive to the extraordinary enrichment of Cd in T1 contain three aspects as high level of Cd in acid-insoluble residues of bedrocks, large proportion of Cd of acid-soluble phase in the bulk rock and low loss rate of Cd in T1.In addition, for the soil layer formed by the accumulation of acid insoluble residues in bedrocks, T1 is the starting point for its development and evolution.The higher the content of Cd is in T1, the higher it is usually in the soil layer, reflecting the development characteristics of general weathering profile.This study might deepen the understanding of geochemical behavior of Cd in karst environment, and provide reference for regional Cd pollution risk assessment based on geological genesis and establishing its cleaning level.