Soil vegetation atmosphere transport (SVAT) model plays an important role in studying the interaction and relationship between atmospheric water, plant water, surface water, soil water and groundwater, plant water consumption process and ecological water demand, feedback mechanism between ecosystem and local climate, interaction mechanism between soil moisture and vegetation, and restoration and reconstruction of ecological environment. SVAT model has developed from single layer model to double layer model and multi-layer model after about half a century development of "bucket" model, biophysical model and biochemical model.