Abstract: The expansive soil of highway reconstruction project was improved by using weathered sand which was widely distributed in Yichang. Through an indoor swell-shrink index test, a conclusion could be drawn that the improved expansive soil could significantly inhibit the swell-shrink characteristics. Through an indoor CBR test, another conclusion could be drawn that expansive soil mixed with weathered sand could obviously improve the CBR value and reach the standard of subgrade filler. The influence of different initial dry density and different sand proportion influence on CBR value of expansive soil were discussed. The results showed that: the initial dry density and the proportion of mixing sand had great influence on CBR value. At a certain initial dry density, the CBR value increased with the increase of sand ratio. At a certain sand proportion, the CBR value increased with the increase of initial dry density. CBR value and initial dry density expressed power relation. When initial dry density was small, CBR value and sand ratio expressed the linear relationship; when initial dry density was high, CBR value and sand ratio expressed the exponential function relationship.