A study on the soil-rice system pollution by the Cd-Zn mixture in nature was conducted using the pot-culture method.There existed some differences between the Cd-Zn combined pollution and single-factor pollution of Cd (or Zn) in the soil-rice systems.The differences included changes in the biological yield of riot and the concentrations of Cd and Zn in brown rice and relationship beFween biological yield of rice and Zn/Cd ratios of brown rice.According to the conclusion,.mathematical model for weighting combined pollution of Cd and Zn in soil-rice systema was deduced.The calculation results obtained by applying the model showed that the maximum allowable concentrations of Cd and Zn in the soil under the combined pollution condition were 1.0 and 400mg/kg,respectively.This provided a basis for working out the soil-environmental quality standards for Cd and Zn.