| In order to improve the water and nitrogen utilization efficiency of spring maize in northern Shaanxi, two factors (the period of supplemental irrigation and the amount of nitrogen applied) were set up in this study. Four periods were set for supplemental irrigation, including the stage of jointing and tasseling (I1), the stage of jointing and grain filling (I2), the stage of tasseling and grain filling (I3), and the stage of jointing, tasseling, and grain filling (I4), and the total irrigation volume of I1, I2, I3, and I4 treatments was 2 250 m3·hm-2, and the number of irrigation times was 4, 5, 5, and 7 times, respectively. Nitrogen fertilizer application was set at two levels, which were 20% (240 kg·hm-2, F2) and 40% (180 kg·hm-2, F1) less than the local conventional N application, and the control treatment was irrigated for the whole life cycle, with an irrigation volume of 3 000 m3·hm-2, a number of irrigation times of 10, and N application of 300 m3·hm-2 (CK), which was the local conventional N application. The effects of the period of supplemental irrigation and the amount of nitrogen applied on soil water content, nitrate nitrogen content, corn water consumption, yield and water, and nitrogen use efficiency were studied. The results showed that the water\|sensitive period of spring maize in northern Shaanxi was from the nodulation period to the grouting period. Supplemental irrigation affected the water content of the 0~40 cm soil layer. Nitrogen application increased the nitrate\|nitrogen content of the 0~40 cm soil layer by an average of 28.65%~38.64%, but it had no significant effect on the soil water content and water consumption. The appropriate period of supplemental irrigation promoted the growth and development of spring maize. Supplementary irrigation was suitable for the maize in the nodulation period and the staminate pumping period in arid and sandy areas of northern Shaanxi. Corn plant height, stem thickness, and leaf area index reached the maximum value, the values of which were 247.01~255.67 cm, 24.18~24.49 mm, and 4.28~4.48, respectively. The treatments (I1F2) with supplemental irrigation at the nodulation and stamen pulling stages and 20% N reduction had the highest yields (except CK) of 11 640.10 kg·hm-2 and 12 644.27 kg·hm-2, which amounted to 84.19% and 91.97% of the CK treatments, respectively, and the optimal water and nitrogen utilization efficiency, which was increased by 2.32% to 22.71% compared with CK. Therefore, to improve the water and nitrogen use efficiency of maize and obtain higher yields, the recommended supplemental irrigation and fertilization program is to concentrate on supplemental irrigation at the nodulation and staminate pulling stages under the condition of 20% reduction of local conventional nitrogen application (240 kg·hm-2, F2), with the irrigation quota of 2 250 m3·hm-2 and the number of irrigation times of 4, which is urgently needed in the I1F2 treatment. |