By using the quadratic general spinning design, pot experiments were conducted to study the comprehensive effect of the stage and rate of N fertilizer application under different status of soil moisture on winter wheat yield systematically. The results showed that the mathematical model established based on the result of experiments is significant. By analysing the mathematical model, the soil moisture, tillering and jointing stage were thought to be the remarkable factors, while the influencing sequence from large to small is： soil moisture ＞ tillering stage ＞ jointing stage ＞ milking stage ＞ seedling stage; The interaction effects exist between different factors.