Relationship between crop water stress index(CWSI) and soil water content in irrigated winter wheat field was investigated at the Irrigation Experiment Station of the Northwestern Science and Technical University of Agriculture and Forestry during the cropping season from October 2000 to July 2001.Based on the formula for calculation of evapotranspiration of a crop under water stress and the definition of CWSI, a CWSI-and SWCC-based equation for estimat ion of soil water content in the winter wheat field at different vegetative stages was worked out using the Dooreboos model (D-M) and Kang Shaozhong model (K-M).The experiment results show: the D-M and K-M both overestimated soil moisture during the seedling-regreening stages and the error ratio reached 70% and 50%, respectively; and the K-M was inclined to overestimate while D-M was inclined to downestimate soil moisture during the regreening-maturing stage and the error ratio could reach 15% and 30%, respectively.