Designing the comparative model experiment,we study the treatment effect of high and low liquid limit clay with vacuum preloading method,esp.the applicability of vacuum preloading method to treat high liquid limit clay in a project and the treatment effect for the two kinds of clay (high and low liquid limit) samples with this method.The result indicates that the moisture content and void ratio of clay samples decreased obviously;The density and strength of them also improved obviously;The volume compression ratio of high liquid limit clay is 47.4%,and the volume compression ratio of low liquid limit clay is 22.9%.It is applicative to treat high liquid limit clay with vacuum preloading method in this project,and the treatment effect is obviously.