【Objective】The purpose of this article is to study mineral composition and cation exchange capacity (CEC) of the colloids and non-colloids in the two red soils collected from Hunan and Hainan provinces, separately, and adsorption behavior of Cu(II), Cd(II) and Pb(II)on thecolloids and non-colloids, too.【Method】 Soil colloidal and non-colloidal fractions were separated from bulk soils using sedimentation method, where particles in the upper portion of the suspension are collected as colloids at fixed time intervals after stirring. X-ray diffraction analysis was performed to determine mineral compositions of the colloids and non-colloids in the red soils. Free Fe and Al oxides were extracted with the DCB method and determined using ICP-AES. The batch method was used to investigate adsorption and desorption of Cu(II), Cd(II) and Pb(II) on and from soil colloids and non-colloids. Un-buffered salt of 1.0 mol L^-1 NaNO₃ was used to desorb pre-adsorbed heavy metals from soil colloids and non-colloids. 【Result】X-ray diffraction analysis shows that the colloids in the two red soils were composed mainly of secondary minerals with 1:1-typed kaolinite in dominancy and little of primary minerals.The contents of 2:1 typed minerals, such as vermiculite and hydro-mica in the soil colloids decreased with increasing soil development degree, while the content of kaolinite changed oppositely. The non-colloids in the two red soils contained mainly quartz and some other primary minerals.Soil Fe and Al oxides accumulated mainly in the soil colloids. The contents of free Fe and Al oxides were much higher in the soil colloids than in the soil non-colloids. For example, the content of free Fe oxide was as high as 78.03 g kg^-1 in the colloids and only 9.93 g kg^-1 in the non-colloids of the red soil from Hunan. The colloids in the two red soils were also much higher than, or 12 times as high as the non-colloids of the soils in CEC. The isothermal adsorption experiment indicates that the colloids were significantly higher than the non-colloids in adsorption capacity and affinity for Cu(II), Cd(II) and Pb(II), and the colloids of the red soil from Hunan was higher than those of the red soil from Hainan in adsorption capacity, which was consistent with mineral composition and CEC of the colloids of the two red soils. Cd(II) was adsorbed by soil colloids and non-colloids mainly through electrostatic attraction, however both electrostatic and non-electrostatic adsorptions were important mechanisms contributing significantly to adsorption of Cu(II) and Pb(II) on soil colloids and non-colloids. 【Conclusion】The secondary minerals and Fe/Al oxides are mainly distributed in the colloids of the two red soils. The colloids are much higher than the non-colloids in the two red soils in CEC, and hence in adsorption capacity and affinity for these heavy metals.