This paper deals with response of crop yields to water resource allocation. Some approaches for calculation and analysis of the effects of water allocation for agriculture are presented as follows: response analysis; analytic function and systems analysis. On the basis of experimental data of relationship between crop yield and water allocation obtained by the Water Conservacy Division of Xing Tai prefecture, Hebei Province, in the North China Plain, by using computer the authors examine the mathmatical models involved in this paper. The calculation results from the suggested approaches coincide fairly well with exsisted experiences in water management of the examined areas. In addition, the calculation shows that the contribution rate of watering to crop yield among the ofher factors influencing crop production accounts for 30-40% on an average. In the North China Plain the futher agriculture development has faced difficult condition of water shortage for a long time. In such case a countermeasure of scientific allocation of agricultural water resources is of great significance. We think, that the methods adopted by the authors and some results involved in this paper are likely to be useful and helpful for making a desirable water allocation decision.