This paper deals with the distribution and transformation of cadmium species in rhizosphere and nonrhizosphere of wheat and rice in red soil and yellow brown soil using a rhizobox or rhizobag and a sequential extraction procedure for the speciation of Cd.Results showed that predominant species of Cd in two soils are not same. EXC-Cd(exchangeable-Cd) is the most important form in red soil while in yellow brown soil Carb-Cd (bound to carbonates) is the most important.In red soil,the contnet of FMO-Cd (bound to iron and manganese oxides) and OM-Cd (bound to organic matter) in rhizosphere of rice are higher than those in nonrhizosphere,which may he due to the activity of rice root and the action of microorganisms on the root surface.The interaction between Pb and Cd showed that the content of EXC-Cd is higher in the presence of Pb in both rhizosphere and nonrhizosphere.the content of OM-Cd,however,is much lower in the presence of Pb.