Abstract: Based on the analysis of experimental data at Guilin Station for late rice,the models of water pro duction function (WPF) for rice and its regularity of temporal and spatial variation are studied in a systematical way.The key problem of use WPF is how to expand the water sensitivity index (WSI).Based on the regularity of the variation of WSI in the Jensen model for rice,the cumulative function of WSI with a growing curve is given out and the characteristics of this function are analyzed,so the problem of conversion WSI be tween different time step are solved.The regularity of the variation of water sensitivity indices with the climate and soil conditions are investigated,especially,the relationships between WSI,the reference evapo transpiration (ET0),and the available soil moisture are presented.Thus,the principle and methods for widening the ranges of time and space for applying the water production function of rice and the principle and methods for drawing the isogram of WSI based on the isogram of ET0 and the soil map are developed.