Expansive clay behaves like mechanical performances of multi-fissures, and deterioration with the changing moisture. To ensure the safe operation of foundation, the effects of intensive water migration on earth constructions founded on semiarid area, have therefore been received much more attention together with the global warming and climate changes. Herein, analytical models considering respectively liquid water and water vapor migration were presented to address changes in moisture content of unsaturated expansive clay under various water content gradients. Moreover, measured data obtained from migration experiments performed under various water content gradients in a closed system, were utilized to check the validity of analytical equations. Results indicate that the migration of both water vapor and mixed water shows nonlinear relationships with time and location. For the expansive clay with low moisture content, major components of migration water was water vapor, which accounted for 83.61-88.62%; while for the clay with higher water content, the liquid water was dominant migration of water due to more free water around the soil particles. The proposed model is helpful to investigate moisture migration law in the unsaturated expansive clay.