Study of Cu adsorption and desorption processes on Red soil(R) and Sajong black soil(SB) is carried out.The results exhibit that SB has higher Cu adsorption quantity than R,and Cu desorption percentage from SB is also higher than that from R.It means that Cu is more easily exchanged by MgCl₂ from IB than from R.In the pH range from 3.5 to 7.5,Cu adsorption in the two soils increases with increasing pH,and shows as of S-shape.Effect of o-Phenylenediamine(o-PD) on Cu adsorption and desorption in the two soils shows that presence of o-PD increases Cu adsorption in R but not changes it obviously in SB, meanwhile,Cu desorption percentage increased correspondingly.Although o-PD does not change Cu adsorption quantity in SB,it changes Cu adsorption process strongly,which can be recognized from Cu desorption percentage from SB.