In the present work,desorption of copper ions adsorbed by variable charge soils was studied.Four variable charge soils,i.e.,Ali-Haplic Acrisol,Ferrali-Haplic Acrisol,Rhodic Ferralsol and Hyper-Rhodic Ferrasol collected from south China,were used.As contrast,two constant charge soils,i.e.,Haplic Luvisoil and Phaeozems collected from Nanjing and Harbin respectively,were also used.The results showed that the copper ions adsorbed by variable charge soils could be desorbed by deionized water.When the adsorbed copper ions were desorbed at different pH,a pH~desorption rate curve could be ob tained.A peak with maximum desorption rate could occur on the curve at a certain pH value.When the pH of soil suspension was higher than this pH value,the desorption rate decreased with the increase in pH.When the pH was lower than this pH value,the desorption rate decreased with the decrease in pH.For different variable charge soils,this pH value was related to the content of iron oxides in soils.The higher the content of iron oxides,the higher this pH value.After removal of copper ions which could be desorbed by deionized water,the residual copper ions adsorbed could be desorbed by dilute solution of NaNO₃. For different variable charge soils,the higher the content of iron oxides and the higher the concentration of electrolyte,the more difficult the desorption of the residual copper ions adsorbed.On the contrary,the copper ions adsorbed by constant charge soils could not be desorbed by deionized water,but could be desorbed by electrolyte solution.The higher the concentration of electrolyte,the greater the ability of desorption of electrolyte.It is suggested that the mechanism of adsorption of copper ions by variable charge soils was different from that by constant charge soils.