Abstract: Loess has the collapsibility characteristic. Loess can have the phenomenon of unstability when it is used as foundation materials. The technique of using strengthening materials cushion to improve water stability and strength of loess foundations has been widely applied. In this test, cushions made of lime, fly ash and cement are added into loess separately. The moisture content, density, dry density, Specific Surface Area(SSA) and Cation Exchange Capacity(CEC) of the loess at different places in vertical direction are measured. Results indicate that the lime, fly ash and cement cushion all have considerable impact on the moisture content, density, SSA and CEC of adjacent loess(10～15cm),changing the microstructure and enhance the water stability of the loess. The closer to the cushion, the smaller the moisture content, SSA and CEC are and the greater the density is Lime cushion has the best effect. It can reduce over 4% of the moisture content, increase 1.0～1.5g cm-3 of the loess density. Effects of fly ash are weaker and cement the weakest. Additionally, the SSA and CEC have a linear increment relationship. In the present test, the rate between SSA and CEC of the three tests is controlled between 6.5～7.5.