From the angles of modification rate,soil layers,and temperature,CrO₄^2- adsorption characterist ics were studied of the soil samples gathered from the tillage layer(TLLS)and clay layer of lou soil(CLLS)modified with cetyltrimethylammonium bromide(CTMAB)and cetyltrimethylammonium bromide+sodium dodecylsulphonate(CTMAB+ SDS)mixture at various rates.The results show that CrO₄^2- equilibrium adsorption amounts(EAA)in the soil samples increased with the CrO₄^2- equilibrium concentration;the adsorption isotherms appeared in the shape of L in the modified soils and of S in the unmodified soil.In terms of adsorption of CrO₄^2- the soil samples from both layers were in the order of 100CB>120CS>50CB>CK.CrO₄^2- adsorption in unmodified TLLS increased faster than that in unmodified CLLS with the increase in CrO₄^2- equilibrium concentration.The EAA of CrO₄^2- in modified CLLS were higher than that in modified TLLS,however,the difference in soil affinity to CrO₄^2- between modified CLLS and modified TLLS decreased with the increase in modification rate.CrO₄^2- adsorption in unmodified soils increases with the temperature,and the effect was stronger on unmodified CLLS than on unmodified TLLS,indicating increase in temperature promotes CrO₄^2- special adsorption on clay mineral.The CrO₄^2- adsorption rate from 20 to 40 on modified soils did not vary much with the increase in CrO₄^2- equilibrium concentration.With rise in temperature,CrO₄^2- adsorption on modified TLLS decreased while the CrO₄^2- adsorption on modified CLLS was related to both modifier and modification rate.