Abstract: Crop water deficit determines irrigation amount and schedule. Using data from field experiments during winter wheat seasons in 2005~2006 and 2006~2007, leaf area index model, soil water infiltration model and crop water requirement model were developed. Then using daily meteorological data during winter wheat seasons for 1951~2001 in Xinxiang of Henan Province (with consideration for the effects of evapotranspiration, precipitation and irrigation), effective precipitation utilization was simulated for each winter wheat season via soil water balance. Based on analysis of relationship between precipitation and effective precipitation during winter wheat season, effective precipitation was calculated at different time-scales. Based on the models for simulating winter wheat water requirement and effective precipitation, a suitable winter wheat water deficit evaluation model was isolated for Xinxiang of Henan Province