Abstract: Irrigation water and nitrogen fertilizer are key factors governing N, P, K uptake by crops. By studying on different combinations of irrigation water and nitrogen fertilizer which consist of six levels of irrigation water and five levels of N fertilizer, the experiment showed that treatments with high levels of irrigation water and high levels of nitrogen fertilizer were unfavorable for N uptake by winter wheat, while maize was fertilizer tolerable crop and the amount of N uptake by maize increased with nitrogen fertilizer when irrigation water remained constant. When irrigation water was in low level (such as: level of W0 or W1), the amount of N uptake by maize grain was very low which ranged from 0 to 17.3kg/hm2 and was independent of applied nitrogen fertilizer, while the amount of N uptake by wheat grain reached as high as 36 6 to 154.2kg/hm2. The curve of P uptake by both winter wheat and maize was similar to that of N uptake. However, the amount of K uptake by both of them increased with irrigation water, especially for maize. Moreover, most of absorbed K disturbed in the straw. Therefore, it is very important for us to publicize returning straw back to the farm field after harvest.