This paper presents the properties of oxide surfaces in soil colloids, including zero point of charge (ZPC), titration curves,amount of hydroxyl(OH) released, and adsorption of NH₄⁺ and Cl^- under various pH.The results showed that as compared with the properties of siloxane surface in montmo-rillonite, the oxide surfaces supplid larger amount of variable charge, the sesquioxide in soils increased the ZPC, but the permanent negative charge and organic matter decreased the ZPC of sons. As clay acids, the proton on oxide surfaces dissociated gradually, so the titration curues showed no inflexions. The density of hydroxy and hydrous group on oxide surfaces which responded to specific adsorption of ion were higher.So far as the chemical formula is concerned, the oxide surfaces in soils are commonly Si-OH, Al-OH and Fe-OH. They can coexist to one kind of soil. The Si-OH suh-surfaces of oxide with low ZPC usually supply negative variable charge, the Al-OH and Fe-OH sub-surfaces with high ZPC supply positive variable charge.