Abstract: The soil water and the fertilizers are the basic materials of the crop development and growth and also the main physical elements which limit the world agriculture.A great number of researches on the response of the dryland crop to the coupling of the soil water and fertilizer has been worked out since 1990' in the northern drought region of China.On the base of those researches,the present paper shows that the extent of the effect of soil water and fertilizers on the dryland crop changes with the relative balance between the soil water and fertilizers' quantity.