The paper analyzed the speciality and vulnerability of hydrology in southwest karst irrigated area from hydrology of karst and irrigation area.According to the hydrologic characteristics in southwest karst irrigated area,a distributed hydrological model for karst irrigated area was developed based on SWAT(Soil and Water Assessment Tool).The epi-karst zone water cycle module,underground river system module,canal seepage module and irrigation function of pond were added into SWAT,and the irrigation water move...