The effects of organic acids on Cd 2+ sorption desorption in testing soil colloids were studied by batch methods. The results showed the maximum amount of Cd 2+ 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 Cd 2+ added, the amount of Cd 2+ sorption was generally characterized as peak like curves with the increase of organic acids concentration. When organic acids and Cd 2+ simultaneously were introduced 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 Cd 2+ sorption, and higher concentration of them decreased the Cd 2+ sorption amount. The effect of Cd 2+ 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 Cd 2+ 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 Cd 2+ desorption as well as distribution ratio of Cd 2+ desorbed by KNO 3 and by DTPA on surfaces of testing soil colloids.