Abstract: Due to the spatial variability of soil hydraulic properties and hydrological factors, field scale models with one-dimensional structure were not applicable to the regional scale modeling. A distributed model, which is named as GSWAP, was developed for simulating soil water flow and salt transport on a regional scale by closely coupling the Soil-Water-Atmosphere-Plant (SWAP) model and ArcInfo. The data of GSWAP can be efficiently pre/post processed based on the strong capabilities of spatial data analysis and processing in ArcInfo. The study area was divided into subunits through the combination of soil type, land use, climate and water table depth conditions. Each subunit was supposed to be an equivalent homogenous system with a set of effective soil hydraulic parameters, which were obtained by using the Genetic Algorithms coupled with SWAP model. Finally，the GSWAP model was applied to the Yonglian Irrigation System, Hetao Irrigation District of Inner Mongolia as a case study. Results showed that the GSWAP model could be efficiently used to simulate the soil water and solute dynamics on a regional scale.