SWAT (Soil and Water Assessment Tool) model is an advanced, physically based and distributed hydrological model for watersheds, which has been developed rapidly in recently years. It is feasible to simulate hydrological and physical processes at the large and middle scale watersheds over long periods of time. This paper described the characteristics of SWAT model, summarized the advantages of the water resource management and application in natural watershed and the existent problems in irrigation districts with intensive artificial interferences after the comment on the researches of hydrological modeling and water resource management worldwide, and put forwards the research directions and application prospects of SWAT model on the water cycle of irrigation districts, water-saving reconstruction and other fields, and provided a new research tool for comment on water resource reasonable management and water-saving irrigation.