Abstract: Based on the theory of the planetary boundary layer and the soil-water dynamics, one dimensional soil-atmosphere coupled numerical model is proposed. The evaporation process in soil-atmosphere system is simulated by the model. The results show that the evaporation can be divided into three stages with the variety of soil moisture near the surface. Soil property is an important influence factor of this process. Finally, paper discusses the variety of the evzporation process with the amount of geostrophic wind speed and solar radiation.