Abstract: The California bearing ratio (CBR) is an important index to evaluate the performances of the subgrade and pavement materials in expressways. Generally, the CBR<> value of clay is not enough for design and construction. Lime is an effective and commonly used admixture that can remarkably improve the physical and mechanical properties and strength of the clay. In order to study the influence of lime content on the CBR value, series of physical and mechanical tests on the clay from an expressway in Jiangsu are carried out. Based on the tests results, the influences of the lime content on the physical and mechanical properties of the clay are analyzed. The variaton rules of the CBR value and the main influence factors are also discussed.