Abstract: To identify the source and analyze the enrichment degree of soil Cd in the limestone distribution areas of Guizhou Province, the geochemical baseline values of soil Cd formed in different geological ages are obtained by standardized method, and the geoaccumulation index is used for evaluation. The results show that the baseline values of Cd in the soil formed from the Permian and Carboniferous limestone are obviously higher than those of the soil formed from limestone of other geological ages. The comparison between the baseline values of Cd in soil and average content of Cd in rocks shows that the naturally weathered rocks are the main source of soil Cd in limestone areas. According to the evaluation results of geoaccumulation index, the pollution of soil Cd in limestone areas of Guizhou is generally at a low level.