Abstract: A dynamic model for crop dry matter production response to daily available soil water and nitro gen was presented.Field experiments were carried out at Yongledian water saving station,Beijing.Using in formation of accumulative dry mater of winter wheat with full supply of water and nitrogen,we estimated the function of winter wheat to soil water and nitrogen based on the experimental data.With the simulated model parameters we calculated the dry mater production under various irrigation and nitrogen conditions.Good agreements between simulated and measured dry mater accumulation process were obtained.