The absolute and relative concentrations for six forms of or fractions of Cd (exchangeable,bound to carbonates, weakly-bounded. exchangeable plus weakly-bounded, bound to Fe-Mn oxides,and bound to organic matter sulfides) in eight main soil types in China were measured. The regional differentiation situations of various forms of Cd are identified Analytical results indicate that exchangeable forms of Cd and exchangeable plus weakly-bounded forms of Cd have obvious regional differentiation Characteristics. Based on these differentiation rules and the combination features, and by using traditional synthetic inductive method and the principal component analysis method, we divide the concentration distribution s of the two forms of Cd into three categories. The absolute and relative concentrations for six forms of or fractions of Cd (exchangeable, bound to carbonates, weakly-bounded. Exchangeable plus weakly-bounded, bound to Fe-Mn oxides, and bound to organic matter sulfides) in eight main soil types in China were measured. The regional differentiation situations of various forms of Cd are identified Analytical results indicate that exchangeable forms of Cd and exchangeable plus weakly-bounded forms of Cd have obvious regional differentiation Characteristics. Based on these differentiation rules and the combination features, and by using traditional synthetic inductive method and the principal component analysis method, we divide the concentration distribution s of the two forms of Cd into three categories.