The effects of organic acids on Cd²⁺ sorption desorption in testing soil colloids were studied by batch meth ods.The results showed the maximum amount of Cd²⁺ sorption by yellow brown soil,red soil and latosol was 43.7,16.8 and 1.58 mmol kg^-1 respectively.At the same concentration of Cd²⁺ added,the amount of Cd²⁺ sorption was generally characterized as peak like curves with the increase of organic acids concentration.When organic acids and Cd²⁺ simultaneously were intro duced in testing systems(competitive sorption),lower concentration of oxalic acid(<0.5~2 mmol L^-1) or citric acid(<0.025~0.2 mmol L^-1) promoted Cd²⁺ sorption,and higher concentration of them decreased the Cd²⁺ sorption amount.The effect of Cd²⁺ sequential sorption on the soil colloids previously adsorbed organic acids(sequential sorption) was almost same as that of competitive sorption,however,the variation of both amount of Cd²⁺ competitive sorption and sequential sorption were not same.Its reason was related to content of residual organic acids in both sorption systems.The results of desorption tests demonstrated that the concentration of oxalic acid impacted total amount and total rate of Cd²⁺ desorption as well as distribution ratio of Cd²⁺ desorbed by KNO₃ and by DTPA on surfaces of testing soil colloids.