The study of soil ecological stoichiometry has mainly focused on surface soils. Exploring the nutrient content and stoichiometric characteristics of deep soils in karst areas helps us to understand the intrinsic relation mechanism and provides scientific evidence for making full use of fractured soil. We analyzed soil nutrient content, nutrient supply intensity, stoichiometric ratios, and their inter-relations at different soil depths in a karst plateau mountain area of China. Soil nutrient supply capacity was relatively low in the study area. The nitrogen and potassium supply capacity was highest in the surface layer, while phosphorus supply capacity was highest in deep soil. Carbon, nitrogen, phosphorus and potassium made varying contributions to the ecological stoichiometric ratios. Soil nitrogen and phosphorus were found to be deficient in the karst plateau mountain area of China. There was certain coordination between nutrient supply intensity and ecological stoichiometric ratios.