A field experiment was conducted to understand the effect of reducing irrigation amount and urea on summer maize yield and soil water, taking summer maize as the research object in Yangling of Shaanxi Province. The organic fertilizer with high organic matter content and strong water retention performance developed by the research group was selected, combined with two levels of irrigation (full irrigation W1 and deficit irrigation W2). According to the principle of equal nitrogen, the organic fertilizer and inorganic fertilizer were mixed with different ratios (F1:100% inorganic fertilizer, F2:24% organic fertilizer+76% inorganic fertilizer and F3:48% organic fertilizer+52% inorganic fertilizer), and the effects of irrigation amount and organic and inorganic fertilizers on water use efficiency and yield of summer maize were studied. The results showed that under W1, the grain yields of F2 and F3 treatments increased by 4.8%~6.3% compared with F1; under W2, the grain yield of organic fertilizer treatment increased by 1.8%~2.3%. Under the same irrigation level, organic fertilizer treatment significantly increased soil water storage at harvest stage (P<0.05), providing a certain humidity for winter wheat germination and growth. The application of organic fertilizer had a significant effect on the plant height at the three-leaf stage and the small trumpet stage, but had no significant effect on the plant height at other stages. The results of this study showed that the treatment of deficit irrigation (W2) and organic fertilizer (F2) was better, which was an effective scheme for summer maize planting. This findings could provide a scientific basis for the optimal management of irrigation and fertilization in the Guanzhong Plain and other similar areas.