Soil evaporation is an important component of land water circle. In general, it is controlled by the soil properties and climate conditions. Usually most researches of soil evaporation focus on the evaporation calculation methods, the impacts of irrigation and management on soil evaporation, and the ratio of evaporation in evapotranspiration. The interior vapor transport beneath the soil surface in the soil evaporation process is ignored. In this work, we propose that the vapor transfer in the unsaturated soil under isothermal and nonisothermal conditions should be studied based on the enhanced diffusion theory of vapor. An enhancement factor model under water content gradient at isothermal condition will be developed. Combining it to the enhancement factor model under temperature gradient, the total soil water vapor transport model was established. It is capable of describing the vapor transport process and evaporations at different soil layers under transient conditions. During the experiment, the heat pulse technique and blue dye tracing will be used. From the dynamic monitoring of primary drying front, secondary drying front and dry surface layer, the interior dynamic process of soil evaporation will be illustrated. Both laboratory and field experiments will be conducted to study soil evaporation and vapor transport. Our measurements and models are useful in understanding the water vapor and liquid water dynamics in the soil evaporation process, and can improve the current models of coupled heat and water transport in the soil.