Abstract: By using the regional evapotranspiration (ET) model, rGIS-ET, the relationship between evapotranspiration in wheat field and the ground water level in Beijing-Tianjin Corridor in April from 1992 to 2001 was analyzed. The results show that the spacial variations of ET in a county are significant, the water consumption of wheat field trends to reduce in recent 10years, but the groundwater level sustainablly decreases because the supply is slowly. The seasonal change of groundwater level is closely related to the water used by winter wheat, the spacial change of ET may indirectly reflect the amount of groundwater.