Abstract: he strength of cement-stabilized soil comes mainly from the cementing effect of the cementhydrates. Cement-stabilized soil samples, made from four kinds of selected soil, were tested for analysingthe composition of the liquid, and detecting the cement hydrates in it, etc. It was revealed that in ce-ment-stabilized soil, liquid may not be Ca（OH）₂ saturated, and if so the higher the amount of CaO andOH￣- absorbed by the soil,the lower the concentration of Ca￣（++） and OH￣- in the liquid of cement-stabilized soil and the less the cement hydrates grow, so the poorer the strength of the cement-stabilized soil, and vice versa. Based on the above analysis, a model of hardening reaction in cement-stabilzed soil was proposed.