Abstract: The limestone soils in five different regions are selected as the research object in grassland ecological conditions in Guizhou Karst Area according to the physical and chemical as well as the genesis characters of the soils. The factors that affect soil development are discussed, the diagnostic horizons and diagnostic characteristics of the soil are determined. Among them, the soil diagnostic horizons involve the Mollic epipedon, Cambic horizon, Argic horizon and so on; the diagnostic characteristics involve the thermic temperature regmie, perudic moisture regime, isohumic property, humic property, base saturation, lithology of the carbonate rocks, ferric property, calcaric property etc. And then, the soils are classified. The results show that the five soils belong to the subgroups of Chinese soil taxonomy in lithology, they are typic black-lithomorphic isohumosols, humic carbonati-perudic cambosols and humic carbonati-perudic argosols.