Abstract:With six tests of expansive soils for the roadbeds,which come from Ningming section of Nanning—Youyiguan Highway in Guangxi Autonomous Region,and Cili section of Changde—Zhangjiajie Highway in Hunan Province,respectively,are analyzed under different weather conditions such as dewatering,overcast,sunshine and precipitation. The different dewatering boundaries,the densities of roadbed,the accumulated water contents are considered for the roadbed. The moisture contents variation,water permeation and evaporation in the expansive soils roadbed are also researched. The achieved results can provide some useful references for the design and construction of expansive soils roadbed.